server-del do not return early if CA renewal master cannot be changed

Early return prevented adding last warning message in the method:
   "Ignoring these warnings and proceeding with removal"

And thus `check_master_removal` in `test_server_del` did not work.

https://pagure.io/freeipa/issue/7517

Signed-off-by: Petr Vobornik <pvoborni@redhat.com>
Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>

ipaserver/plugins/server.py

@@ -523,14 +523,11 @@ class server_del(LDAPDelete):
                       "leave your installation without a CA."),
                     ignore_last_of_role)
 
+            # change the renewal master if there is other master with CA
             if ca_renewal_master == hostname:
                 other_cas = [ca for ca in ca_servers if ca != hostname]
 
-                # if this is the last CA there is no other server to become
-                # renewal master
-                if not other_cas:
-                    return
-
+                if other_cas:
                     self.api.Command.config_mod(
                         ca_renewal_master_server=other_cas[0])