The pipeline was quite meagre in both stages and the number of groups.
This has been improved. Performance is not yet optimal, but to limit
this from sliding further this slippery slope, a hard limit has been
set.

Removed all the unnecessary include of `WaitForAjax` and `ApiHelpers` in the specs.
Removed unnecessary usage of `api:true`

Use detailed_status effectively. Remove unnecesarry context(nest). Add new context in merge_requests_controller_spec.rb and fix a bug. Correct description of spec.

Fix broken test

[ci skip]