ipa-cert-fix: improve handling of 'pki-server cert-fix' failure
'pki-server cert-fix' has a known and expected failure when the DS
certificate is expired. 'ipa-cert-fix' handles this by
optimistically ignoring the CalledProcessError and continuing when
the DS certificate was up for renewal.
This heuristic is a bit too optimistic. If 'pki-server cert-fix'
fails due and returns nonzero due to some other, more serious error
(as has been seen in the wild[1]), 'ipa-cert-fix' continues then
fails later with a more confusing error, for example:
[Errno 2] No such file or directory:
'/etc/pki/pki-tomcat/certs/27-renewed.crt'
[1] https://bugzilla.redhat.com/show_bug.cgi?id=1930586
Improve the heuristic by also checking whether output files
corresponding ot all of the "extra" certificate that we asked
'ipa-cert-fix' to renew, do indeed exist and are X.509 certificates.
Fixes: https://pagure.io/freeipa/issue/8721
Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>