[CLANG][DWARF] Do not emit -ggnu-pubnames for LLDB tuning, unless...

[CLANG][DWARF] Do not emit -ggnu-pubnames for LLDB tuning, unless -ggnu-pubnames is specified. (#83331)

When -gsplit-dwarf is passed in clang emmmits -ggnu-pubnames which
results in
.debug_gnu_pubnames/..debug_gnu_pubtypes being generated.
This is used by GDB, but not by LLDB.
Changed so that these sections are not emitted for LLDB tuning, unless
flag
is passed explicitly.