Use nasqueron/postgres-sentry image

Summary:
PostgreSQL for Sentry should use our nasqueron/postgres-sentry image,
ie PostgreSQL 9.6 + wal2json

Fixes T1818.

Test Plan: Deployed on docker-002, database started again, Sentry up.

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1818

Differential Revision: https://devcentral.nasqueron.org/D2969