Provide options for an external Postgres

[williamdes]

Problem Statement

As a user I prefer to run myself the Postgres and Clickhouse DBs.
It also makes me sure the DB servers still run when I down/up Sentry.

A lot of the setup relies onto having Postgres as a container for upgrades.
Can an external option be done ?
Same for Clickhouse but much less a priority.

Solution Brainstorm

Currently I comment out the Postgres container and tweaks envs.
And also have to comment all your upgrade lines, and check on each new release. (this is quite the most problematic)

Solution: ask Sentry itself for a DB connection with Python and run the migration ?

[aldy505]

I'm gonna backlog this and have a debate with @BYK about doing a documentation vs providing a .patch file 😆