DEVOPS-1790 - Add Cleanup RC Branch workflow

[vgrassia]

Type of change

• [ ] Bug fix
• [ ] New feature development
• [ ] Tech debt (refactoring, code cleanup, dependency upgrades, etc)
• [X] Build/deploy pipeline (DevOps)
• [ ] Other

Objective

• Card

This PR adds the Cleanup RC Branch workflow.

Code changes

• .github/workflows/cleanup-rc-branch.yml: Add Cleanup RC Branch workflow

Before you submit

• [ ] I have checked for linting errors (npm run lint) (required)
• [ ] I have added unit tests where it makes sense to do so (encouraged but not required)
• [ ] This change requires a documentation update (notify the documentation team)
• [ ] This change has particular deployment requirements (notify the DevOps team)

[bitwarden-bot]

Checkmarx One – Scan Summary & Details – cbe4d5f9-b3e3-4f61-90d8-640e1acedf54

New Issues

Severity	Issue	Source File / Package	Checkmarx Insight
	Unpinned Actions Full Length Commit SHA	/cleanup-rc-branch.yml: 21	Pinning an action to a full length commit SHA is currently the only way to use an action as an immutable release. Pinning to a particular SHA helps...