ci: ensures tests are run on push

[bartoszmajsak]

Description

Unit tests job is currently only executed on PRs, leaving pushes on e.g. incubation branch untested. This can lead to issues like the one described in #1235

This PR enables GH Action to be run also for push events.

How Has This Been Tested?

You can use act to test GH Actions locally instead of running them on your fork.

act "on: push" -j unit-test -P ubuntu-latest=ghcr.io/catthehacker/ubuntu:act-latest

Screenshot or short clip

Merge criteria

• You have read the contributors guide.
• Commit messages are meaningful - have a clear and concise summary and detailed explanation of what was changed and why.
• Pull Request contains a description of the solution, a link to the JIRA issue, and to any dependent or related Pull Request.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work

[zdtsw]

Put a "on hold" label, so we can have some disucssion before merge this change.
Mostly, this involves work process of how PR should be merged, if we enforce all branch up-to-date before PR merge, or how to prevent stable branch gets merged in.

[zdtsw]

this is also related to "#1221 (comment)"

[ykaliuta]

Put a "on hold" label, so we can have some disucssion before merge this change. Mostly, this involves work process of how PR should be merged, if we enforce all branch up-to-date before PR merge, or how to prevent stable branch gets merged in.

Should the workflow just filter by branch?

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ykaliuta, zdtsw

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