Resolve "Make 'Run Pipeline' and 'Get started with Pipelines' buttons working consistently in 'CI/CD > Pipelines' page"

What does this MR do?

Change the two views of pipelines page (list and empty) to fix both Run Pipeline and Get started with Pipelines buttons, using the following model:

Consider that:

• hasCiEnabled is true if you have a gitlab-ci.yml file (or custom one), or if you have Auto DevOps enabled

• canRunPipeline is true if you have permissions to run pipelines (e.g.: you are Developer)

These are all the possible combinations:

• List view

  • Show Run Pipeline if hasCiEnabled and canRunPipeline

  • Show Get started with Pipelines if not hasCiEnabled and canRunPipeline

• Empty view

  • Show Build with confidence paragraph if canRunPipeline

  • Show Run Pipeline if hasCiEnabled and canRunPipeline

  • Show Get started with Pipelines if not hasCiEnabled and canRunPipeline

  • Show There are no pipelines to show if not canRunPipeline

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Screenshots (if relevant)

Permission to run pipelines, no CI/CD configured

Permission to run pipelines, CI/CD configured

No permission to run pipelines

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #37426 (closed)