restore: clear httpd ccache after restore

so that httpd ccache won't contain old credentials which would make ipa CLI fail with error:

 Insufficient access: SASL(-1): generic failure: GSSAPI Error: Unspecified GSS failure.  Minor code may provide more information (Decrypt integrity check failed)

https://fedorahosted.org/freeipa/ticket/4726

Reviewed-By: Petr Viktorin <pviktori@redhat.com>

ipaserver/install/ipa_restore.py

@@ -314,6 +314,8 @@ class Restore(admintool.AdminTool):
                 self.log.info('Restarting SSSD')
                 sssd = services.service('sssd')
                 sssd.restart()
+                http = httpinstance.HTTPInstance()
+                http.remove_httpd_ccache()
         finally:
             try:
                 os.chdir(cwd)