Automate generation of US PubSec weekly maintenance issue

What

Adds automation to generate an issue to track maintenance of US PubSec tenants every week on Friday.

Why

This helps reduce toil in creating the same issue template every week and ensuring it's triaged and assigned appropriately.

Dry run output

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* Title: Weekly US PubSec tenant maintenance [2024-04-22]
* Description: # Maintenance Procedure

## Amp Clusters

### uspubsecops

Changes to the Amp cluster are only needed if any environment variables need to be updated (e.g. StackArmor config)
and can be deployed whenever needed, preferably before any tenant maintenance window has started.

- [ ] Update AMP CICD variables for any recent code changes (if needed)

## Tenants

### Customer 0/gdguat

Maintenance window time: 2024-04-25 00:00-23:00 UTC

- [ ] Merge any renovate MRs to upgrade Instrumentor version
  - [ ] Ensure deployment pipeline runs successfully
- [ ] Merge any renovate MRs to upgrade Gitlab version
  - [ ] Ensure deployment pipeline runs successfully
- [ ] Validate recent features are working (if needed)

/confidential
/due 2024-04-26
/label ~"team::US PubSec" ~"team-tasks" ~"type::maintenance" ~"toil" ~"workflow-infra::Ready"
/epic https://gitlab.com/groups/gitlab-com/gl-infra/-/epics/1227
/milestone https://gitlab.com/groups/gitlab-com/gl-infra/-/milestones/243
/cc @gitlab-dedicated/uspubsec
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Closes https://gitlab.com/gitlab-com/gl-infra/gitlab-dedicated/team/-/issues/2446