Avoid multiple calls to LDAP when querying group memberships

Closes #44558

Signed-off-by: Pedro Igor <pigor.craveiro@gmail.com>

federation/ldap/src/main/java/org/keycloak/storage/ldap/mappers/membership/group/GroupLDAPStorageMapper.java

@@ -780,6 +780,8 @@ public class GroupLDAPStorageMapper extends AbstractLDAPStorageMapper implements
                 return cachedLDAPGroupMappings.stream();
             }
 
+            cachedLDAPGroupMappings = Set.of();
+
             List<LDAPObject> ldapGroups = getLDAPGroupMappings(ldapUser);
             if (!ldapGroups.isEmpty()) {
                 GroupModel parent = getKcGroupsPathGroup(realm);