By default, PostgreSQL only records the first 1024 characters of a SQL
query. This means for long queries, we often lose the source of the
query, which makes it difficult to track down expensive queries, such as
one described in https://gitlab.com/gitlab-org/gitlab/-/issues/292047.

Increasing the `track_activity_query_size` in PostgreSQL will help, but
this requires a reboot of the database. To avoid needing to depend on
https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/12314, we
prepend the comment as described in
https://github.com/basecamp/marginalia#prepend-comments.

We disable this for tests because a number of tests expect raw SQL to
start the string.