Upgrade process should not crash on named restart

When either dirsrv or krb5kdc is down, named service restart in
ipa-upgradeconfig will fail and cause a crash of the whole upgrade
process.

Rather only report a failure to restart the service and continue
with the upgrade as it does not need the named service running. Do
the same precaution for pki-ca service restart.

https://fedorahosted.org/freeipa/ticket/3350