Consolidate labels ~"blocked" and ~"workflow::blocked" into ~"workflow::blocked"

We will be adjusting this one-off automation so that the notification impact is lessened to consolidate the workflowblocked and ~"blocked [deprecated in favor of workflow : : blocked]" labels.

Action Plan

• Rename ~workflow::blocked to ~workflow::blocked-migrate
• Rename ~blocked [deprecated in favor of workflow : : blocked] to ~workflow::blocked
• Update policy and dry-run to convert ~workflow::blocked-migrate to ~workflow::blocked
• Inform in #development and #product in Slack of migration for Board migration
• Dry Run: https://gitlab.com/gitlab-org/quality/triage-ops/-/jobs/273196469
• Migrate issues and MRs on 8/15 at 2:00 pm UTC: https://gitlab.com/gitlab-org/quality/triage-ops/-/jobs/273221474

Scope of Impacted Resources

• 34 issues - https://gitlab.com/groups/gitlab-org/-/issues?scope=all&utf8=%E2%9C%93&state=all&label_name[]=workflow%3A%3Ablocked-migrate
• 1 MR - https://gitlab.com/groups/gitlab-org/-/merge_requests?scope=all&utf8=%E2%9C%93&state=all&label_name[]=workflow%3A%3Ablocked-migrate
• 10 boards - (validated with https://gitlab.com/api/v4/groups/gitlab-org/boards)
  • In dev / In review
  • Health - Workflow
  • Geo Kanban Build
  • Monitor kick off - Workflow
  • Plan Kanban
  • 12.3 Package
  • Team Planning Kanban
  • Certify Kanban
  • Miranda Fluharty
  • Manage::Analytics::Product Process

This MR will be a one-off run of the pipeline and is not to be merged.

Closes #252 (closed)