Add template selection to scan execution actions

What does this MR do and why?

Add template selection to scan execution actions

• add criteria to allow users to select between the default and latest security job template
• remove yaml if default is selected

Changelog: added

EE: true

MR acceptance checklist

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

Project-level

1. Upload a GitLab Ultimate license
2. Enable the project feature flag echo "Feature.enable(:scan_execution_policies_with_latest_templates)" | rails c
3. Navigate to a project/group => Secure => Policies => New policy => Scan execution => Under "Action", click "Add new criteria" => Template criteria
4. Verify the yaml updates
5. Change the value
6. Verify the yaml updates
7. Navigate to yaml mode => Modify the template => Navigate back to rule mode
8. Verify rule mode is disabled for an invalid template value
9. Verify rule mode is changed for a valid template value

Group-level

1. Upload a GitLab Ultimate license
2. Enable the group feature flag echo "Feature.enable(:scan_execution_policies_with_latest_templates_group)" | rails c
3. Navigate to a group => Secure => Policies => New policy => Scan execution => Under "Action", click "Add new criteria" => Template criteria
4. Verify the yaml updates
5. Change the value
6. Verify the yaml updates
7. Navigate to yaml mode => Modify the template => Navigate back to rule mode
8. Verify rule mode is disabled for an invalid template value
9. Verify rule mode is changed for a valid template value

Related to #415427 (closed)