Improvements to Project overview UI

What does this MR do?

• Add crossed bell icon when notifications for project are set to disabled
• Move "non-existing" statistic buttons (like add README, add CHANGELOG to the end of buttons list)
• Change the icon for "Auto devops" to a gear as it doesn't actually link to a file.

What are the relevant issue numbers?

#55025 (closed) (follow-up of #51243 (closed))

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer

Closes #55025 (closed)