Dev task: reduce duplication in GitHub Actions

**Describe the task**
With the switch to multiple Python packages we have a lot of duplication related to testing in integration.yml and post_merge_integration.yml. We should investigate parameterizing these actions.

**Acceptance Criteria**
- [ ] first
- [ ] second
- [ ] third

**Additional context**
- Add any other context about the task here.
- Or here

Start by comparing integration.yml and post_merge_integration.yml, focusing on the duplicated testing setup introduced for multiple Python packages. Identify which repeated workflow steps can be parameterized and confirm the existing test coverage and workflow behavior. Done means the duplicated testing configuration is reduced while both workflows continue to run the required package tests.

Written by the indexing model from the issue text.