Fix flakyness in citus_split_shard_by_split_points_deferred_drop (#6819)

In CI we would sometimes get this failure:
```diff
 -- The original shard is marked for deferred drop with policy_type = 2.
 -- The previous shard should be dropped at the beginning of the second split call
 SELECT * from pg_dist_cleanup;
  record_id | operation_id | object_type |                               object_name                                | node_group_id | policy_type
 -----------+--------------+-------------+--------------------------------------------------------------------------+---------------+-------------
+        60 |          778 |           3 | citus_shard_split_slot_18_21216_778                                      |            16 |           0
        512 |          778 |           1 | citus_split_shard_by_split_points_deferred_schema.table_to_split_8981001 |            16 |           2
-(1 row)
+(2 rows)
```

Replication slots sometimes cannot be deleted right away. Which is hard
to resolve, but luckily we can filter these cleanup records out easily
by filtering by policy_type.

While debugging this issue I learnt that we did not use
`GetNextCleanupRecordId` in all places where we created cleanup
records. This caused test failures when running tests multiple times,
when they set `citus.next_cleanup_record_id`. I tried fixing that by
calling GetNextCleanupRecordId in all places but that caused many
other tests to fail due to deadlocks. So, instead this adresses
that issue by using `ALTER SEQUENCE ... RESTART` instead of
`citus.next_cleanup_record_id`. In a follow up PR we should
probably get rid of `citus.next_cleanup_record_id`, since it's
only used in one other file.

src/test/regress/expected/citus_split_shard_by_split_points_deferred_drop.out

@@ -28,7 +28,7 @@ SET citus.next_placement_id TO 8610000;
 SET citus.shard_count TO 2;
 SET citus.shard_replication_factor TO 1;
 SET citus.next_operation_id TO 777;
-SET citus.next_cleanup_record_id TO 511;
+ALTER SEQUENCE pg_catalog.pg_dist_cleanup_recordid_seq RESTART 511;
 SET ROLE test_split_role;
 SET search_path TO "citus_split_shard_by_split_points_deferred_schema";
 CREATE TABLE table_to_split(id int PRIMARY KEY, int_data int, data text);
@@ -64,10 +64,10 @@ SELECT pg_catalog.citus_split_shard_by_split_points(
 
 -- The original shard is marked for deferred drop with policy_type = 2.
 -- The previous shard should be dropped at the beginning of the second split call
-SELECT * from pg_dist_cleanup;
+SELECT * FROM pg_dist_cleanup WHERE policy_type = 2;
  record_id | operation_id | object_type |                               object_name                                | node_group_id | policy_type
 ---------------------------------------------------------------------
-       512 |          778 |           1 | citus_split_shard_by_split_points_deferred_schema.table_to_split_8981001 |            16 |           2
+       526 |          778 |           1 | citus_split_shard_by_split_points_deferred_schema.table_to_split_8981001 |            16 |           2
 (1 row)
 
 -- One of the physical shards should not be deleted, the other one should.
@@ -90,8 +90,12 @@ SELECT relname FROM pg_class where relname LIKE '%table_to_split_%' AND relkind
 
 -- Perform deferred drop cleanup.
 \c - postgres - :master_port
-CALL citus_cleanup_orphaned_resources();
-NOTICE:  cleaned up 1 orphaned resources
+SELECT public.wait_for_resource_cleanup();
+ wait_for_resource_cleanup
+---------------------------------------------------------------------
+
+(1 row)
+
 -- Clenaup has been done.
 SELECT * from pg_dist_cleanup;
  record_id | operation_id | object_type | object_name | node_group_id | policy_type

src/test/regress/sql/citus_split_shard_by_split_points_deferred_drop.sql

@@ -24,7 +24,7 @@ SET citus.next_placement_id TO 8610000;
 SET citus.shard_count TO 2;
 SET citus.shard_replication_factor TO 1;
 SET citus.next_operation_id TO 777;
-SET citus.next_cleanup_record_id TO 511;
+ALTER SEQUENCE pg_catalog.pg_dist_cleanup_recordid_seq RESTART 511;
 SET ROLE test_split_role;
 SET search_path TO "citus_split_shard_by_split_points_deferred_schema";
 
@@ -51,7 +51,7 @@ SELECT pg_catalog.citus_split_shard_by_split_points(
 
 -- The original shard is marked for deferred drop with policy_type = 2.
 -- The previous shard should be dropped at the beginning of the second split call
-SELECT * from pg_dist_cleanup;
+SELECT * FROM pg_dist_cleanup WHERE policy_type = 2;
 
 -- One of the physical shards should not be deleted, the other one should.
 \c - - - :worker_1_port
@@ -62,7 +62,7 @@ SELECT relname FROM pg_class where relname LIKE '%table_to_split_%' AND relkind
 
 -- Perform deferred drop cleanup.
 \c - postgres - :master_port
-CALL citus_cleanup_orphaned_resources();
+SELECT public.wait_for_resource_cleanup();
 
 -- Clenaup has been done.
 SELECT * from pg_dist_cleanup;