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

The `projects/:id/pipelines` exposed a lot of extra details
that are superfluous and it was taking extra resources to fetch them.

To get more details about a pipeline, use
`projects/:id/pipelines/:pipeline_id`.

Restore changes for api spec files

Fix error in rspec Users

Delete extra space Repositories-spec

The coverage wasn't exposed yet, now it is but only for detailed
requests to save queries on the database.

Add a new endpoint in the new API for creating a new pipeline, and return the details of that pipeline.