[lldb] deactivate some tests on older SDKs (#147768)
https://github.com/llvm/llvm-project/pull/144913 was reverted because
some of the Darwin tests were failing on SDKs prior to `15.0`.
Only the x86 bots run on macOS `14.0`. The aarch64 ones run on macOS
`15.0`.
In this patch, we deactivate the failing Darwin tests on older SDKs
(prior to `15.0`).
