Implement mini graph pipeline to use gl-dropdown [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

In the original implementation of the stages in mini pipelines the dropdown to show jobs in a stage used jQuery to handle events.

This change aims to replace this implementation with the component gl-dropdown from gitlab-ui.

As the pipeline is widely used, we want to be able to turn it off, so it can be easily turned on/off. This change is behind feature flag: ci_mini_pipeline_gl_dropdown.

This change will be visible in:

• Pipelines list (e.g. http://gdk.test:3000/root/my-project/-/pipelines)
• MR widget (e.g. http://gdk.test:3000/root/my-project/-/merge_requests/3)
• Commit -> Pipelines list (e.g. http://gdk.test:3000/root/my-project/-/commit/90899dd422cfa8608ee206e028128cdabe58d596/pipelines)

☝ I suggest turning "Show whitespace changes" off as there were some big indent changes!

Screenshots (strongly suggested)

Pipeline List	MR page	Commit page (see pipelines list)

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

Related to #299902 (closed)