Resolve "On MR creation set `approvals_required: 0` for policy approval rules"

What does this MR do and why?

Previously, we set the approvals_required to 1 as we were waiting for the security violations to be executed.

On creation/update, we want to set the approvals_required to 0 as we now have a mergeability check which waits for the security violations to run. Once the violations are run, the approvals_required will be updated.

To test:

1. Turn on feature flag policy_mergability_check and ensure you have a Docker runner

2. In the project, ensure that main is a protected branch.

3. Create .gitlab-ci.yml:

   include:
     - template: Jobs/Secret-Detection.gitlab-ci.yml
   
   test-job:
     stage: test
     script:
       - echo "Testing"

4. Go to Secure -> Policies -> New policy. Select "Merge request approval policy".

5. Switch to the .yaml mode and use the following YAML:

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

6. Configure with a merge request && merge

7. Go back to the project and open a new MR

8. The MR should be blocked with security evaluation check and the security rule is optional

9. Create a .env file with `AWS_TOKEN=AKIAZYONPI3G4JNCCWGQ'

10. Push, and wait for the CI to run, and the approval rules should be required

Related to #478862 (closed)