[llvm] Reland "Add a pass to collect dropped var stats for MIR" (PR #117044)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-nvptx64-nvidia-ubuntu` running on `as-builder-7` while building `llvm` at step 6 "test-build-unified-tree-check-llvm".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/160/builds/9420

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

```
Step 6 (test-build-unified-tree-check-llvm) failure: test (failure)
******************** TEST 'LLVM-Unit :: CodeGen/./CodeGenTests/98/154' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/unittests/CodeGen/./CodeGenTests-LLVM-Unit-2633647-98-154.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=154 GTEST_SHARD_INDEX=98 /home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/unittests/CodeGen/./CodeGenTests
--

Note: This is test shard 99 of 154.
[==========] Running 2 tests from 2 test suites.
[----------] Global test environment set-up.
[----------] 1 test from DroppedVariableStatsMIR
[ RUN      ] DroppedVariableStatsMIR.InlinedAt

--
exit: -11
--
shard JSON output does not exist: /home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/unittests/CodeGen/./CodeGenTests-LLVM-Unit-2633647-98-154.json
********************


```

</details>

https://github.com/llvm/llvm-project/pull/117044