Update Auto DevOps' auto-deploy-image to v2.12.0

What does this MR do?

This adds several new features and bugfixes to Auto Deploy. See gitlab-org/cluster-integration/auto-deploy-image@v2.6.0...v2.12.0 for details.

Manual QA

Pipeline for this .gitlab-ci.yml, pasted below for convenience:

# Auto DevOps stages
stages:
  - build
  - test
  - deploy  # dummy stage to follow the template guidelines
  - review
  - dast
  - staging
  - canary
  - production
  - incremental rollout 10%
  - incremental rollout 25%
  - incremental rollout 50%
  - incremental rollout 100%
  - performance
  - cleanup

variables:
  ROLLOUT_RESOURCE_TYPE: deployment

# Minimal jobs to test the modified templates
include:
  - template: Jobs/Build.gitlab-ci.yml
  - template: Security/DAST.gitlab-ci.yml
  - project: gitlab-org/gitlab
    ref: update-ado-image-to-v2-12-0
    file: 
      - lib/gitlab/ci/templates/Jobs/DAST-Default-Branch-Deploy.gitlab-ci.yml
      - lib/gitlab/ci/templates/Jobs/Deploy.gitlab-ci.yml

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.