[Clang][OpenMP] Bug fix Default clause variable category (#165276)
In the default clause taking care of new comments in the previous
"Support for Default clause variable category"
[157063](https://github.com/llvm/llvm-project/pull/157063) and adding a
new test case.
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Co-authored-by: Sunil Kuravinakop <kuravina@pe31.hpc.amslabs.hpecorp.net>