Execute migration with gitlab PG user
Currently, we execute migrations using the PG user supplied when creating the clone. This is a superuser by default and it doesn't resemble 1:1 what's going to happen later in production: In prod, we use the gitlab
user, which is a) not a superuser and b) has limited permissions, e.g. to certain PG system views.
Proposal: Instead of using a PG superuser to execute migrations in the test pipeline, let's switch to using the gitlab
user.
We'd have to alter the login details for the user in order to use it in the pipeline. This would need to happen while we prepare the thin clone.