Remove artifacts page feedback banner

What does this MR do and why?

Remove artifacts page feedback banner

We have enough feedback for now, so we can remove the banner component and the callout entry for it, references to it, specs for it, etc.

Changelog: removed

Screenshots or screen recordings

Before	After
A banner asking for feedback is shown at the top of the artifacts page	The banner has been removed

How to set up and validate locally

1. if you've dismissed the artifacts_management_page_feedback_banner callout in your testing environment, bring it back:

   1. git checkout master
   2. navigate to a project, and in the sidebar choose Build => Artifacts
   3. there should be a feedback banner at the top of the page
   4. if there isn't, run this command:

   echo 'User.find_by(username: "root").callouts.find_by(feature_name: "artifacts_management_page_feedback_banner").destroy()' | rails c

2. git checkout 423939-remove-artifacts-feedback-callout-banner

3. navigate to a project, and in the sidebar choose Build => Artifacts (or refresh the page if you're already there)

4. there should not be a feedback banner at the top of the page any more

to run tests

yarn install && yarn jest ci/artifacts

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 #423939 (closed)