Align release date calculation with documentation

[marcusburghardt]

Description:

To improve the predictability of release dates, it was agreed to start the stabilization phase on the last Monday of the first Month in the quarter.
Consequently, the release is expected two weeks after the stabilization period is started.

Rationale:

In alignment to #12232

Review Hints:

./utils/release_helper.py stats
./utils/release_helper.py release --message

[github-actions]

Start a new ephemeral environment with changes proposed in this pull request:

Fedora Environment

Oracle Linux 8 Environment

[github-actions]

🤖 A k8s content image for this PR is available at:
ghcr.io/complianceascode/k8scontent:12240
This image was built from commit: 918149d

Click here to see how to deploy it

If you alread have Compliance Operator deployed:
utils/build_ds_container.py -i ghcr.io/complianceascode/k8scontent:12240

Otherwise deploy the content and operator together by checking out ComplianceAsCode/compliance-operator and:
CONTENT_IMAGE=ghcr.io/complianceascode/k8scontent:12240 make deploy-local

[codeclimate]

Code Climate has analyzed commit 918149d and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 59.4% (0.0% change).

View more on Code Climate.

[marcusburghardt]

/packit test

[Mab879]

/packit rebuild-failed

[Mab879]

/test images

[openshift-ci]

@marcusburghardt: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/images	918149d	link	true	/test images

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.

[Mab879]

Works great, thanks.

Waving Automatus Sanity as it not part of this PR and waving the Prow images as this only modifies a script used by upstream.