Unify all MR widget text colors and background colors

* Removes darker background color for `skipped` status
* Makes all MR widget text gray
Before:   
![Screen_Shot_2016-11-18_at_7.52.16_AM](/uploads/4ee715aec9c453c5cfe1f259049adbde/Screen_Shot_2016-11-18_at_7.52.16_AM.png)
After:   
![Screen_Shot_2016-11-18_at_7.52.05_AM](/uploads/ea14d713a4e7d837bac4576815451dce/Screen_Shot_2016-11-18_at_7.52.05_AM.png)

Closes #24639

See merge request !7571