chainlink CCIP-1496 Delete expired logs by the block

Motivation

Delete expired logs should use block_timestamp instead of created_at. created_at is generated when inserting a block into the database. These values can be completely different for different nodes because of the

different clocks
inserting logs to DB at different times due to outage, replay etc In this case, block_timestamp is the real value on "when" the block was produced and should be the same for all nodes.

This is a very similar case to what was fixed some time ago for the read layer https://github.com/smartcontractkit/chainlink/pull/10743

Additionally, we can get rid of the created_at index, because after this change filtering by created_at is not used at all. One index less should save some time during insert/delete operations on evm.logs table. The only scenario that might be a problem here is running replay from block older than the defined retention. Prune will start removing logs that are just replayed, this won't be a problem when we keep it filtering by created_at

No big difference between deleting by block_timestamp and created_at. Removing around ~90k logs

-- created_at
 Delete on logs l  (cost=0.56..201494.41 rows=92352 width=12) (actual time=6069.856..6069.857 rows=0 loops=1)
   ->  Nested Loop  (cost=0.56..201494.41 rows=92352 width=12) (actual time=0.067..2268.151 rows=1309224 loops=1)
         ->  Seq Scan on log_poller_filters  (cost=0.00..54.99 rows=277 width=60) (actual time=0.013..0.620 rows=271 loops=1)
               Filter: (evm_chain_id = '11155111'::numeric)
               Rows Removed by Filter: 1021
         ->  Index Scan using idx_evm_logs_ordered_by_block_and_created_at on logs l  (cost=0.56..725.26 rows=196 width=60) (actual time=1.103..7.819 rows=4831 loops=271)
               Index Cond: ((evm_chain_id = '11155111'::numeric) AND (address = log_poller_filters.address) AND (event_sig = log_poller_filters.event) AND (created_at <= (statement_timestamp() - '6415:33:20'::interval)))
 Planning Time: 0.422 ms
 Execution Time: 6069.896 ms
(9 rows)

-- block_timestamp

 Delete on logs l  (cost=0.56..193585.58 rows=92282 width=12) (actual time=5568.214..5568.215 rows=0 loops=1)
   ->  Nested Loop  (cost=0.56..193585.58 rows=92282 width=12) (actual time=0.048..1760.326 rows=1309284 loops=1)
         ->  Seq Scan on log_poller_filters  (cost=0.00..54.99 rows=277 width=60) (actual time=0.013..0.480 rows=271 loops=1)
               Filter: (evm_chain_id = '11155111'::numeric)
               Rows Removed by Filter: 1021
         ->  Index Scan using evm_logs_by_timestamp on logs l  (cost=0.56..696.71 rows=196 width=60) (actual time=0.011..5.941 rows=4831 loops=271)
               Index Cond: ((evm_chain_id = '11155111'::numeric) AND (address = log_poller_filters.address) AND (event_sig = log_poller_filters.event) AND (block_timestamp <= (statement_timestamp() - '6415:33:20'::interval)))
 Planning Time: 0.416 ms
 Execution Time: 5568.253 ms
(9 rows)