Update doorkeeper buttons to pajamas

What does this MR do and why?

Update doorkeeper buttons to pajamas

• use pajamas::button component

Changelog: changed

Screenshots or screen recordings

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Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested. From !77621 (merged)

Testing the full OAuth2 flow is a bit tricky locally because you need to setup an OAuth2 provider. In this case we don't need to test the full flow since we are just changing the styling of the authorize panel so we can follow the instructions below:

1. Login to GitLab as an Admin and navigate to /admin/applications/new
2. Fill out the form with the following:
   • Name - Foo bar
   • Redirect URI - http://foo.bar
   • Check api under Scopes
3. Navigate to /oauth/authorize?access_type=online&client_id=<Application ID>&redirect_uri=http%3A%2F%2Ffoo.bar&response_type=code&scope=api. Make sure you update <Application ID> to the Application ID provided in the previous step

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 #417817 (closed)