pylint: Drop never used __remove_lightweight_ca_key_retrieval_custodia

__remove_lightweight_ca_key_retrieval_custodia has been added in
8700101d9, but it was never used.

Caught by Pylint:
```
ipaserver/install/cainstance.py:1308: [W0238(unused-private-member),
CAInstance.__remove_lightweight_ca_key_retrieval_custodia]
Unused private member
`CAInstance.__remove_lightweight_ca_key_retrieval_custodia(self)`)
```

Fixes: https://pagure.io/freeipa/issue/9117
Signed-off-by: Stanislav Levin <slev@altlinux.org>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>

ipaserver/install/cainstance.py

@@ -27,7 +27,6 @@ import enum
 import logging
 
 import dbus
-import ldap
 import os
 import re
 import shutil
@@ -1305,21 +1304,6 @@ class CAInstance(DogtagInstance):
         os.chmod(keyfile, 0o600)
         self.service_user.chown(keyfile)
 
-    def __remove_lightweight_ca_key_retrieval_custodia(self):
-        keyfile = os.path.join(paths.PKI_TOMCAT,
-                               self.service_prefix + '.keys')
-        keystore = IPAKEMKeys({'server_keys': keyfile})
-        # Call remove_server_keys_file explicitly to ensure that the key
-        # file is always removed.
-        keystore.remove_server_keys_file()
-        try:
-            keystore.remove_keys(self.service_prefix)
-        except (ldap.CONNECT_ERROR, ldap.SERVER_DOWN):
-            logger.debug(
-                "Cannot remove custodia keys now, server_del takes care of "
-                "them later."
-            )
-
     def add_lightweight_ca_tracking_requests(self):
         try:
             lwcas = api.Backend.ldap2.get_entries(