ipareplica/server: Always cleanup root IPA cache

The cleanup of the root IPA cache was depending on the result of the
ipaserver_enable_ipa and ipareplica_enable_ipa tasks. Instead of
"when: something.changed" a handler should be used instead. As
"/root/.ipa_cache" should be removed always (same in command line) the
removal of the file has been moded into the always section and does not
need a when anymore.