[llvm] [NFC][VPlan] Extract BTC-related tests into `vplan-based-stride-mv-btc.ll` (PR #214047)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-aarch64-darwin` running on `doug-worker-5` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/47392

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: Transforms/LoopVectorize/vplan-based-stride-mv-btc.ll' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 8
/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/opt < /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/vplan-based-stride-mv-btc.ll -p loop-vectorize -force-vector-width=4 -S      -enable-mem-access-versioning=false  2>&1 | /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/vplan-based-stride-mv-btc.ll --check-prefix COMPARE-NO-MV
# executed command: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/opt -p loop-vectorize -force-vector-width=4 -S -enable-mem-access-versioning=false
# note: command had no output on stdout or stderr
# executed command: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/vplan-based-stride-mv-btc.ll --check-prefix COMPARE-NO-MV
# note: command had no output on stdout or stderr
# RUN: at line 11
/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/opt < /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/vplan-based-stride-mv-btc.ll -p loop-vectorize -force-vector-width=4 -S      -enable-mem-access-versioning=true  2>&1 | /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/vplan-based-stride-mv-btc.ll --check-prefix COMPARE-LAA-MV
# executed command: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/opt -p loop-vectorize -force-vector-width=4 -S -enable-mem-access-versioning=true
# note: command had no output on stdout or stderr
# executed command: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/vplan-based-stride-mv-btc.ll --check-prefix COMPARE-LAA-MV
# note: command had no output on stdout or stderr
# RUN: at line 14
/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/opt < /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/vplan-based-stride-mv-btc.ll -p loop-vectorize -force-vector-width=4 -S      -tail-predication=enabled -tail-folding-policy=must-fold-tail      -enable-mem-access-versioning=false  2>&1 | /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/vplan-based-stride-mv-btc.ll --check-prefix COMPARE-NO-MV-FOLD-TAIL
# executed command: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/opt -p loop-vectorize -force-vector-width=4 -S -tail-predication=enabled -tail-folding-policy=must-fold-tail -enable-mem-access-versioning=false
# note: command had no output on stdout or stderr
# error: command failed with exit status: 1
# executed command: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/vplan-based-stride-mv-btc.ll --check-prefix COMPARE-NO-MV-FOLD-TAIL
# .---command stderr------------
# | /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/vplan-based-stride-mv-btc.ll:133:34: error: COMPARE-NO-MV-FOLD-TAIL-LABEL: expected string not found in input
# | ; COMPARE-NO-MV-FOLD-TAIL-LABEL: define void @non_constant_btc(
# |                                  ^
# | <stdin>:1:1: note: scanning from here
# | opt: Unknown command line argument '-tail-predication=enabled'. Try: '/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/opt --help'
# | ^
# | <stdin>:1:20: note: possible intended match here
# | opt: Unknown command line argument '-tail-predication=enabled'. Try: '/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/opt --help'
# |                    ^
# | 
# | Input file: <stdin>
# | Check file: /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/vplan-based-stride-mv-btc.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |              1: opt: Unknown command line argument '-tail-predication=enabled'. Try: '/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/opt --help' 
# | label:133'0    {                                                                                                                                                search range start (exclusive)
# | label:133'1                                                                                                                                                     error: no match found in search range
# | label:133'2                        ?                                                                                                                            possible intended match
# |              2: opt: Did you mean '--avoid-speculation=enabled'? 
# | label:133'3                                                      } search range end (exclusive)
# | >>>>>>
# `-----------------------------
# error: command failed with exit status: 1
...

```

</details>

https://github.com/llvm/llvm-project/pull/214047