Migrate triggers setting table to Vue

What does this MR do?

Fix for #250312 (closed). Prerequisite work of #42742 (closed)

Migrate triggers settings table to Vue behind feature flag ci_pipeline_triggers_settings_vue_ui Rollout issue: #247486 (closed)

So we can add more functionality to the triggers table we would like to move the table from HAML to Vue.

As a temporary measure, this change loads the data from a JSON string that gets added to the HTML of the page, instead of loading the data via AJAX.

☝ This MR aims to have full feature parity with the current table, and only some minor differences should be noticed by the user.

Settings can be found at http://127.0.0.1:3000/root/autodevops/-/settings/ci_cd#js-pipeline-triggers

TODO

• New Vue specs.
• Try to run the feature tests against new UI.

Technical Choices

• The data is send from the backend to the frontend via a json string in the <div data-triggers="..."/>
  • This is meant to be improved in the feature by having this data being loaded via AJAX.
• A new feature flag ci_pipeline_triggers_settings_vue_ui is introduced.
• Many strings in the old UI are not translated, new string were added to the namespace Pipelines|.

Screenshots

Changes to the UI should be minimal:

before	after

Also, there are changes in the invalid badge appearance:

before	after

This recording shows the 2 versions of the UI active at the same time (new UI at the bottom):

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

touches #42742 (closed)