[llvm] [VPlan] Use APSInt in CheckSentinel directly (NFC). (PR #190534)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

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

Full details are available at: https://lab.llvm.org/buildbot/#/builders/3/builds/30931

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

```
Step 6 (test-build-unified-tree-check-all) failure: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
...
PASS: Clang :: CodeGen/X86/sse41-builtins.c (13 of 90255)
PASS: Clang :: CodeGen/X86/sse41-builtins-constrained.c (14 of 90255)
PASS: Clang :: Driver/arm-cortex-cpus-1.c (15 of 90255)
PASS: Clang :: CodeGen/X86/sse42-builtins.c (16 of 90255)
PASS: Clang :: Driver/arm-cortex-cpus-2.c (17 of 90255)
PASS: Clang :: CodeGen/X86/avx512bw-builtins.c (18 of 90255)
PASS: LLVM :: CodeGen/X86/vector-interleaved-load-i8-stride-8.ll (19 of 90255)
PASS: Clang :: OpenMP/target_simd_codegen_registration.cpp (20 of 90255)
PASS: Clang :: Preprocessor/aarch64-target-features.c (21 of 90255)
PASS: Clang :: OpenMP/target_parallel_codegen_registration.cpp (22 of 90255)
command timed out: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=1393.880734

```

</details>

https://github.com/llvm/llvm-project/pull/190534