[lldb] Remove unused UnwindPlan functions (#134630)
`GetLSDAAddress` and `GetPersonalityRoutinePtrAddress` are unused and
they create a bit of a problem for discontinuous functions, because the
unwind plan for these consists of multiple eh_frame descriptors and (at
least in theory) each of them could have a different value for these
entities.
We could say we only support functions for which these are always the
same, or create some sort of a Address2LSDA lookup map, but I think it's
better to leave this question to someone who actually needs this.
