feat: More cross-track itest assertions

[MichaelThamm]

Issue

• Consider moving everything to a quality_gate method to keep the tests DRY

Solution

Checklist

• I have added or updated relevant documentation.
• PR title makes an appropriate release note and follows conventional commits syntax.
• Merge target is the correct branch, and relevant tandem backport PRs opened.
• Check if replace juju_application is the only (if even) case which causes data loss

Context

Testing Instructions

Upgrade Notes

[MichaelThamm]

We probably don't want this assertion and can say in docs to "run terraform apply until no more changes"