build: update integration tests

[olavloite]

Updates the integration tests based on a number of observations:

1. The migration tests are too slow, as these generate a huge number of different schema versions. These are therefore skipped on production and only executed on the emulator.
2. The with_separate_database tests did not disconnect from the database after it was dropped. This caused occasional Database not found errors.
3. The rename_columns_test did not use DDL batching.
4. ActiveRecord 7.0.6 and 7.0.7 were not included in the tests.