Unblock rules if scanners are defined by pipeline execution policies

What does this MR do and why?

Unblock approval merge request rule for which there are all scanners enforced by pipeline execution policies.

References

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• Depends on Trigger worker on push when the linked PEP proj... (!179502 - merged).

MR acceptance checklist

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Before	After

How to set up and validate locally

1. Enable feature flags pipeline_execution_policy_analyze_configs and unblock_rules_using_pipeline_execution_policies
2. Apply changes from !179502 (merged) until it's merged

   curl https://gitlab.com/gitlab-org/gitlab/-/merge_requests/179502.diff | git apply

3. Create a project SPP
4. In the project, create policy-ci.yml:

   include:
     - template: Jobs/Dependency-Scanning.gitlab-ci.yml
   
   policy-test-job:
     stage: test
     script:
       - echo 'Policy test job 1'

5. Create another project
6. In this project, go to Secure -> Policies and link the project SPP from step 2. as a policy project
7. Create a new pipeline execution policy:

   pipeline_execution_policy:
     - name: Enforced scans
       description: ''
       enabled: true
       pipeline_config_strategy: inject_ci
       content:
         include:
           - project: <path-to-spp-project>
             file: policy-ci.yml

8. Save the policy
9. Create a merge request approval policy, requiring approvals for new dependency_scanning vulnerabilities with an option to unblock rules using execution policies:

   approval_policy:
     - name: Dependency scan approvals
       description: ''
       enabled: true
       rules:
         - type: scan_finding
           scanners:
             - dependency_scanning
           vulnerabilities_allowed: 0
           severity_levels: []
           vulnerability_states: []
           branch_type: protected
       actions:
         - type: require_approval
           approvals_required: 1
           role_approvers:
             - developer
         - type: send_bot_message
           enabled: true
       approval_settings:
         block_branch_modification: false
         prevent_pushing_and_force_pushing: false
         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
       policy_tuning:
         unblock_rules_using_execution_policies: true
   

10. In the project, create a MR (update README.md)
11. Verify that no approvals are required, although the dependency_scanning job didn't run
12. Disable the pipeline execution policy
13. Verify that an approval is required due to missing scanner configuration

Related to #498624 (closed)