Fixed inner page tabs not being scrollable

Phil Hughesrequested to merge
scrollable-secondary-tabs into master

What does this MR do?

Some inner page tabs where not scrollable like the top nav & this caused them to break onto new lines mobile.

This pages include:

  • dashboard/projects
  • project -> merge_requests
  • search
  • project -> milestones
  • project -> pipelines

Screenshots (if relevant)

Page Screenshot
Projects dashboard Screen_Shot_2017-03-24_at_09.43.56
Merge requests Screen_Shot_2017-03-24_at_09.44.31
Milestones Screen_Shot_2017-03-24_at_09.44.55
Search Screen_Shot_2017-03-24_at_09.46.33
Pipelines Screen_Shot_2017-03-24_at_09.55.45

What are the relevant issue numbers?

Closes #18853 (closed)

Merge request reports