EmptyState: Replace bootstrap classes with gitlab-ui classes

Currently, our EmptyState component still relies on bootstrap classes for layout:

Default Compact
Screen_Shot_2021-12-06_at_11.57.53_AM Screen_Shot_2021-12-06_at_12.01.35_PM

This issue is to replace the bootstrap classes with gitlab-ui utility classes to handle layout and responsiveness.

Any style replacements should make sure the components matches the design specs: https://www.figma.com/file/Bp0HvnbtcLcoLYHXbrWwzc/Empty-states?node-id=1%3A2.

Edited by Jarek Ostrowski