[LLDB] [Tests] Downgrade -Wincompatible-pointer-types to a warning in some tests (#158756)

These no longer compile because the warning now defaults to an error
after #157364, so downgrade the error to a warning for now; I’m not
familiar enough with either LLDB or MacOS to fix these warnings properly
(assuming they’re unintended).

GitOrigin-RevId: 9b95e10d5ea6b61e0d9af0a800d63566ae32a2d0