Migrate clipboard buttons

What does this MR do and why?

This migrates a few instances of deprecated_clipboard_button to the newer, Pajamas-compliant, clipboard_button helper.

Migrate to Pajamas compliant buttons in app/vie... (#417837 - closed)

Before	After

• Navigate to a project's mirroring settings at Settings > Repository > Mirroring repositories.
• Setup a Push mirror with SSH public key as the authentication method.

Migrate to Pajamas compliant buttons in ee/app/... (#417865 - closed)

Before	After

• Navigate to a project's mirroring settings at Settings > Repository > Mirroring repositories.
• Setup a Pull SSH mirror.

Migrate to Pajamas compliant buttons in app/hel... (#417802 - closed)

Before	After

• Navigate to any Merge Request.

Migrate to Pajamas compliant buttons in app/vie... (#417843 - closed)

Before	After

• Navigate to a project's Wiki.
• Click on Clone repository (/:group/:project/-/wikis/git_access).

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.