[llvm] [SLP] Better way to filter target-specific tests (PR #106720)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `premerge-monolithic-linux` running on `premerge-linux-1` while building `llvm` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/153/builds/9758

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

```
Step 7 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'RealtimeSanitizer-Unit :: ./Rtsan-x86_64-Test/51/76' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/build/buildbot/premerge-monolithic-linux/build/runtimes/runtimes-bins/compiler-rt/lib/rtsan/tests/./Rtsan-x86_64-Test-RealtimeSanitizer-Unit-1902641-51-76.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=76 GTEST_SHARD_INDEX=51 /build/buildbot/premerge-monolithic-linux/build/runtimes/runtimes-bins/compiler-rt/lib/rtsan/tests/./Rtsan-x86_64-Test
--

Script:
--
/build/buildbot/premerge-monolithic-linux/build/runtimes/runtimes-bins/compiler-rt/lib/rtsan/tests/./Rtsan-x86_64-Test --gtest_filter=RtsanFileTest.OpenCreatesFileWithProperMode
--
/build/buildbot/premerge-monolithic-linux/llvm-project/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors.cpp:225: Failure
Value of: stat(GetTemporaryFilePath(), &st)
Expected: is equal to 0
  Actual: -1


/build/buildbot/premerge-monolithic-linux/llvm-project/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors.cpp:225
Value of: stat(GetTemporaryFilePath(), &st)
Expected: is equal to 0
  Actual: -1



********************


```

</details>

https://github.com/llvm/llvm-project/pull/106720