Remove DisableForeignKeysAndTriggers from our test suite in coder/coder

`DisableForeignKeysAndTriggers` was added to punt some of the work getting our tests running with Postgres instead of the in-memory database (which didn't support foreign key constraints and triggers).

Some of the uses, like in `dbauthz` should get replaced by the mock database, others should get fixed up to satisfay Postgres.

Start by locating every use of DisableForeignKeysAndTriggers in the test suite, with particular attention to dbauthz, and review how the mock database is used. Done means removing the helper, replacing applicable uses with the mock database, and fixing the remaining tests so they satisfy Postgres constraints and triggers.

Scritto dal modello di indicizzazione a partire dal testo della issue.