internal/db: do not run TimescaleDB migrations against singleton database

Created by: slimsag

In our DB testing code we make an assumption that we can run all database migrations against a single testing database. This holds true for frontend and codeintel migrations, because we intentionally designed codeintel migrations to be ran in the same DB for testing/dev purposes only - but this does not hold true for Code Insights which runs a separate TimescaleDB instance (it is easier to run it separately in Docker than install it as a Postgres extension in all of our dev/testing environments.)

This change merely makes it so we don't run TimescaleDB migrations against our singleton testing/dev Postgres DB.

Signed-off-by: Stephen Gutekanst [email protected]