Revert "[MLIR] Add forgotten directory Support to unittests cmake"

This reverts commit 0c553cc1.

This caused a buildbot failure (https://lab.llvm.org/buildbot#builders/197/builds/888).

```
******************** TEST 'ScudoStandalone-Unit :: ./ScudoUnitTest-aarch64-Test/ScudoCommonTest.ResidentMemorySize' FAILED ********************
Script:
--
/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/stage1/projects/compiler-rt/lib/scudo/standalone/tests/./ScudoUnitTest-aarch64-Test --gtest_filter=ScudoCommonTest.ResidentMemorySize
--
Note: Google Test filter = ScudoCommonTest.ResidentMemorySize
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from ScudoCommonTest
[ RUN      ] ScudoCommonTest.ResidentMemorySize
/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/llvm/compiler-rt/lib/scudo/standalone/tests/common_test.cpp:49: Failure
Expected: (getResidentMemorySize()) > (OnStart + Size - Threshold), actual: 707358720 vs 943153152
[  FAILED  ] ScudoCommonTest.ResidentMemorySize (21709 ms)
[----------] 1 test from ScudoCommonTest (21709 ms total)
[----------] Global test environment tear-down
[==========] 1 test from 1 test suite ran. (21709 ms total)
[  PASSED  ] 0 tests.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] ScudoCommonTest.ResidentMemorySize
 1 FAILED TEST
********************
```