Use central release workflow to create and cleanup release branches according to branch-info (#1560)

* Create and cleanup branches as part of release workflow

See https://gardener.github.io/cc-utils/github_actions.html#release-branches
for reference references.

Signed-off-by: Jonas Brand (8R0WNI3) <j.brand@sap.com>

* Adjust `supported-versions-count` to old behaviour in cleanup policy

Signed-off-by: Jonas Brand (8R0WNI3) <j.brand@sap.com>

---------

Signed-off-by: Jonas Brand (8R0WNI3) <j.brand@sap.com>

Author: 8R0WNI3

.github/workflows/create-branch.yaml

@@ -44,6 +44,8 @@ jobs:
       next-version: ${{ inputs.next-version }}
       next-version-callback-action-path: .github/actions/prepare-release
       slack-channel-id: C9CEBQPGE # #sap-tech-gardener
+      create-release-branch: true
+      cleanup-release-branches: true
     permissions:
       contents: write
       packages: write
@@ -59,14 +61,3 @@ jobs:
       name: ${{ needs.release-to-github-and-bump.outputs.component-descriptor.version }}
       strip_patch: true
     secrets: inherit
-
-  create-release-branch:
-    if: ${{ inputs.next-version == 'bump-minor' && inputs.release-version == 'set-prerelease' }}
-    needs:
-      - release-to-github-and-bump
-    uses: ./.github/workflows/create-branch.yaml
-    with:
-      version: ${{ needs.release-to-github-and-bump.outputs.component-descriptor.version }}
-    secrets: inherit
-    permissions:
-      contents: write

.github/workflows/release-cleanup.yaml

@@ -1,5 +1,5 @@
 release-branch-template: release-v$major.$minor # e.g. release-v1.0
 branch-policy:
   significant-part: minor # major, minor, patch
-  supported-versions-count: 2
+  supported-versions-count: 3
   release-cadence: 4w # d (days), w (weeks), y | yr (years)