[llvm] [lldb][test] Mark gtest cases as XFAIL if the test suite is XFAIL (PR #102986)

[Jonas Devlieghere via llvm-commits]

https://github.com/JDevlieghere approved this pull request.

The google test format didn't account for LIT's ability to XFAIL and relied on the unit test binary to return a non-zero exit code for an XFAILed unit test, which is orthogonal. LGTM. 

https://github.com/llvm/llvm-project/pull/102986