migrator: Update drift to not report error without hints

Created by: efritz

Update the migrator drift tooling to only report an error ("drift detected") if it can explicitly list differences. There are some conditions where additional data on the real schema are not reported, but indicates a differences does exist.

This PR eliminates those cases. A follow-up PR should address the conditions where additional tables, columns, etc, can pose a threat to the instance's use of the schema.

Test plan

Tested by hand.