Release workflow should open a PR with changes instead of direct push

[sutaakar]

Right now the release workflow pushes the release changes directly into the branch.
This approach doesn't work out of the box due to the branch protection in repository. As a result branch protection has to be disabled during release.

Release workflow should open a PR instead of pushing changes directly and wait until the PR is merged by OpenShift CI.

Also release workflow should release to Pypi repository as a last step, to make sure that the release flow will pass. The reason is that Pypi release cannot be deleted/reverted.

Also make sure that all created release artefacts (i.e. created release on GitHub and such) are removed in case release workflow fails.