Refactor: libcrmcommon: xml_log_option_full_fledged > pcmk__xml_fmt_full

Replace the public enum with the internal one. Also, remove check for
pcmkxml_fmt_filtered unset. It's never set at the same time as
pcmkxml_fmt_full, so the check is unnecessary.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>