Styling issues in MR widget

Summary

MR widget, which was introduced in %9.2 has couple of styling issues for most of the states, attached are the screenshots of the same.

Steps to reproduce

• Go to any open Merge Request (with Passing, Failing or Running pipeline)
• Notice how things look in MR widget

Screenshots

Merge When Pipeline Succeeds button

Font alignment and color inconsistencies

Group buttons spacing