Add comparison pipelines in bot comments for error cases

What does this MR do and why?

Add comparison pipelines in bot comments for error cases

Related to #467411 (closed)

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

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Before	After

How to set up and validate locally

1. Create a new project
2. Add a .gitlab-ci.yml with the content

build1:
  stage: build
  script:
    - echo "Do your build here"

3. Go to Secure > Policies
4. Click in New policy
5. Select Merge request approval policy
6. change to the yaml mode
7. Copy the yaml content below:

type: approval_policy
name: a
description: ''
enabled: true
rules:
  - type: scan_finding
    scanners:
      - secret_detection
    vulnerabilities_allowed: 0
    severity_levels: []
    vulnerability_states: []
    branch_type: protected
actions:
  - type: require_approval
    approvals_required: 1
    role_approvers:
      - developer
      - maintainer
  - type: send_bot_message
    enabled: true
approval_settings:
  block_branch_modification: true
  prevent_pushing_and_force_pushing: true
  prevent_approval_by_author: false
  prevent_approval_by_commit_author: false
  remove_approvals_with_new_commit: false
  require_password_to_approve: false
fallback_behavior:
  fail: closed

8. Click in Configure with a merge request
9. Merge the the MR
10. Go back to the project created on step 1
11. Create a new MR editing the README file
12. Verify the bot comment about the missing scan contains the Comparison pipelines information