Run only Swift subset of LLDB tests for Linux Smoketest preset

[edymtt]

Addresses rdar://149562580

[edymtt]

Please test with following pull request:
swiftlang/llvm-project#10510

@swift-ci please smoke test

[edymtt]

The filtering works as expected

PASS: lldb-api :: lang/swift/cxx_interop/backward/stepping/TestSwiftBackwardInteropStepping.py (503 of 503)

Testing Time: 47.19s

Total Discovered Tests: 2309
  Excluded         : 1806 (78.22%)
  Unsupported      :  208 (9.01%)
  Passed           :  292 (12.65%)
  Expectedly Failed:    3 (0.13%)

compared to

PASS: lldb-api :: repl/clang/TestClangREPL.py (3116 of 3116)
********************
Failed Tests (1):
  lldb-api :: tools/lldb-server/TestGdbRemoteAttach.py


Testing Time: 158.50s

Total Discovered Tests: 3660
  Skipped          :    1 (0.03%)
  Unsupported      :  713 (19.48%)
  Passed           : 2916 (79.67%)
  Expectedly Failed:   29 (0.79%)
  Failed           :    1 (0.03%)

[adrian-prantl]

Let's cherry-pick that to release/6.2, too!

[adrian-prantl]

Although I suppose, you cannot actually smoke test there...