[CI/CD] Migrate prowjobs out of Neighbor's Prow - Neighbors

[Sawthis]

Description
The prow jobs owned by the Neighbors team have to be removed and if necessary substituted with something else.
To simplify the process here is a list of the issues that should be migrated by Neighbors team.

• Migrate pre-main-check-users-map to Github action #9768
• Implement required checks solution #12285
• [IaC] Remove developer access for terraform planner service account #10075
• Migrate CLA Assistant outside of Prow #11956
• Delete Prow jobs for Prow autobump and deploy #12145
• Remove not needed anymore sap-kyma-workloads GCP project and cleaner Prow jobs #9771
• Migrate GCP resources cleaners to Github actions #9765
• Migrate linters to Github actions #9763
• Remove gardener maintenance Prow jobs #9764
• Delete ci-prow-branchprotector job #9766
• Migrate image-detector-autobump to Github actions #9767
• [PoC] Migrate pre-main-check-users-map from Prow #11828
• Migrate post-test-infra-markdown-index-autobump to Github action #9769
• Implement Image Syncer Job as GitHub Action #11384
• Simplify and consolidate image building in neighbors. #9434
• Get access to the GCP kyma-project to migrate release-template-operator-assets from the Neighbors Prow #9925
• Cleanup Gardener resources and code #9940
• Migrate pre-test-infra-validate-kaniko-build-config to GitHub Actions #10903
• Migrate ci-prow-autobump-jobs Prow job to the Github action #12056