fix: Solution test on pytest-only changes

[MichaelThamm]

Issue

We want to run our integration tests if there are only pytest changes. And this is a backport from this PR:

• feat: Juju v4 support in solution tests #465

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.
• This PR has Terraform product changes and appropriate lifecycle args and moved blocks were added to the terraform/*/upgrades.tf file(s).
• This PR has breaking changes to the product API(s) and I have created an issue in SolQA pipelines to address this.