[#23197] YSQL: pg_partman: Disable Gist index creation

Summary:
Disable creating gist index on `custom_time_partitions` table in pg_partman
as it GIST index creation is not supported.
Jira: DB-12139

Test Plan: jenkins: compile only

Reviewers: jason, skumar

Reviewed By: jason

Subscribers: yql

Differential Revision: https://phorge.dev.yugabyte.com/D36568

src/postgres/third-party-extensions/pg_partman/sql/tables/tables.sql

@@ -83,7 +83,9 @@ CREATE TABLE @extschema@.custom_time_partitions (
     , child_table text NOT NULL
     , partition_range tstzrange NOT NULL
     , PRIMARY KEY (parent_table, child_table));
+/* YB: GIST index not supported
 CREATE INDEX custom_time_partitions_partition_range_idx ON @extschema@.custom_time_partitions USING gist (partition_range);
+*/
 SELECT pg_catalog.pg_extension_config_dump('custom_time_partitions', '');
 
 /*