Create Composite Index for xform_id and id fields

[KipSigei]

Changes / Features implemented

• Create compound Index for xform_id and id fields on the logger_instance table

Steps taken to verify this change does what is intended

Side effects of implementing this change

• Adds a compound index on (xform_id, id) to enhance performance when running a query with ORDER BY and LIMIT clauses on the logger_instance table
• Below are the comparisons in execution time before applying the index and after:
  Before

<db_name>=> EXPLAIN ANALYZE SELECT id, json FROM logger_instance WHERE deleted_at IS NULL AND xform_id IN (some_id) ORDER BY id, xform_id LIMIT 1;
                                                                             QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.56..3908.70 rows=1 width=309) (actual time=1717190.801..1717190.803 rows=1 loops=1)
   ->  Index Scan using logger_instance_pkey on logger_instance  (cost=0.56..20576312.78 rows=5265 width=309) (actual time=1717190.799..1717190.800 rows=1 loops=1)
         Filter: ((deleted_at IS NULL) AND (xform_id = <some_id>))
         Rows Removed by Filter: 30625777
 Planning Time: 0.094 ms
 Execution Time: 1717190.835 ms
(6 rows)


Time: 2142197.397 ms (35:42.197)

After

<db_name>=> EXPLAIN ANALYZE SELECT id, uuid FROM logger_instance WHERE deleted_at IS NULL AND xform_id = <some_id> AND media_all_received ORDER BY id ASC LIMIT 1;
                                                                           QUERY PLAN                                                                            
-----------------------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.56..3.06 rows=1 width=40) (actual time=0.012..0.012 rows=1 loops=1)
   ->  Index Scan using logger_instance_id_xform_id_index on logger_instance  (cost=0.56..13922.40 rows=5575 width=40) (actual time=0.011..0.012 rows=1 loops=1)
         Index Cond: (xform_id = <some_id>)
         Filter: ((deleted_at IS NULL) AND media_all_received)
 Planning Time: 0.098 ms
 Execution Time: 0.023 ms
(6 rows)

Before submitting this PR for review, please make sure you have:

• Included tests
• Updated documentation

Closes #2516