Under high contention, the updating of execution logs query:

UPDATE
  lsif_indexes
SET
  execution_logs = execution_logs || $1::json
WHERE
  id = $2
  AND worker_hostname = $3
  AND state = $4 RETURNING ARRAY_LENGTH(execution_logs, $5)

Was taking multiple seconds due to lock contention on the lsif_indexes_state index.

Running EXPLAIN ANALYZE on Sourcegraph.com under lower contention uses
the primary key index on id, so we don't have an easy way to test the high contention
scenario. Try this alternate query form to see if that fixes the issue.

Test plan

Existing tests continue to pass.

Slowly increase executor count back to 160 and see if lock contention comes up again.