Single writer concurrency control in PQS

[tudor-da]

Description
Ensure that only a single PQS instance can execute writes to a DB to eliminate the risk of state corruption.

[ivanfrolovau]

https://github.com/digital-asset/participant-query-store/blob/main/apps/postgres/document/resources/db/migration/V005__Make_watermark_progression_safer.sql#L32