[lldb/crashlog] Use environment variable to manually set dsymForUUIDBinary (#94517)

In lldb, users can change the `dsymForUUID` binary using the
`LLDB_APPLE_DSYMFORUUID_EXECUTABLE` environment variable.

This patch changes the crashlog to support the same behaviour as lldb
and uses this environment variable to disable `dsymForUUID` lookups in
crashlog test by having it be empty. Since CI bots shoudn't have access
to images on build records, it doesn't make sense to make use of
`dsymForUUID` in tests.

rdar://128953725



Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>