When displaying a project's pipelines
(Projects::PipelinesController#index) we now exclude the coverage data.
This data was not used by the frontend, yet getting it would require one
SQL query per pipeline. These queries in turn could be quite expensive
on GitLab.com.
Given the user can soon have multiple config sources for CI, we now store
what type at the time of the pipeline run we chose. This will give us
insight into what triggered the new pipeline so we can display it to the
enduser.
Now we have a PipelineEntity which is a bit smaller, mostly in bytes
needing to send to the frontend. PipelineDetailsEntity is the default
for the PipelineSerializer, limiting the changes needed.
This commit also incorporates the review.
