Migrate buttons in blob edit view to ButtonComponent

What does this MR do and why?

It updates 2 buttons in app/views/projects/_commit_button.html.haml to be rendered with new ButtonComponent

Screenshots or screen recordings

Works and looks as before

How to set up and validate locally

Go to Project -> Repository -> Files -> Open one of the files for editing (not Web IDE)

Example path

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 #363937 (closed)