Simplify Integration test execution in CI

[potiuk]

When we run all integration tests in CI together on self-hosted runners they are somewhat flaky, however when those tests are run individually on public runners, they are both fast and stable. Also the integration test list has been somewhat duplicated - you had to remember about adding individual integration tests to the separate integration-tests workflow when you added such integration tests.

This PR solves all those problems:

• we always run integration tests individually
• they are all run on public runners no matter what build they are on
• they are run as matrix of jobs and list of tests is extracted via selective checks outputs - no more duplication

---

^ Add meaningful description above
Read the Pull Request Guidelines for more information.
In case of fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
In case of a new dependency, check compliance with the ASF 3rd Party License Policy.
In case of backwards incompatible changes please leave a note in a newsfragment file, named {pr_number}.significant.rst or {issue_number}.significant.rst, in newsfragments.

[potiuk]

I think that should address the recent flakiness observed in main for integration tests. Looks like when we run all integrations together. even our self-hosted runners do not cope well with having all of them started together. Those tests are generally quite fast (< 2 minutes) - so it should be perfectly fine to run them as matrix jobs on Public runners instead - this way we save some self-hsoted runners in main and we should gain back the stablity.

[potiuk]

BTW, This one should address the last "frequent" flakiness observed in main recently.

[potiuk]

This is how it will look like now:

There will be more jobs, but they also will be rather fast and stable