server install: remove duplicate -w option

Remove duplicate -w alias of --admin-password in ipa-server-install and
ipa-replica-install.

https://pagure.io/freeipa/issue/6392

Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>

ipaserver/install/server/__init__.py

@@ -118,6 +118,10 @@ class ServerInstallInterface(client.ClientInstallInterface,
     )
     principal = replica_install_only(principal)
 
+    admin_password = extend_knob(
+        client.ClientInstallInterface.admin_password,
+    )
+
     master_password = knob(
         str, None,
         sensitive=True,