dns_easydns_rm() picked the first id in the search response and ignored
$txtvalue. When two challenge records exist under the same host - for
example when example.com and *.example.com are issued as separate
certificates - a concurrent run's record could be deleted instead of
our own.
Select the record by its rdata instead, following the dns_cf.sh
convention of matching name + value. tr '{' '\n' puts one record per
line, so both _egrep_o branches - egrep -o and the BRE sed fallback -
return the same single id. Without it the sed fallback would return
only the last match, since .* is greedy.
An empty record_id is now treated as "nothing to remove" and returns 0,
rather than being reported as an error.
Also add the credential check that _rm was missing. It deliberately
does not call _saveaccountconf_mutable, as _add already does that.
Co-authored-by: wurzelpanzer <wurzelpanzer@maximolider.net>
