lalpulsar/lib/ReadPulsarParFile.c: remove deprecated XLALReadTEMPOParFileOrig()

To be addressed once !2495 (merged) is merged.

Update: the function with the abort() call is XLALReadTEMPOParFileOrig(), an older TEMPO par file reading code which has been deprecated since 2017. So we might as well remove this function entirely and port code over to the modern function, which is XLALReadTEMPOParFile().