Show error message for permissions failure on MR pipeline

What does this MR do and why?

When running a pipeline on an MR without permissions an unhelpful message was shown. This MR fixes that message for a first iteration towards the larger problem of hiding the button.

Screenshots or screen recordings

before	after

How to set up and validate locally

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

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #348110 (closed)