Change pipeline page layout to fluid

The pipeline page has a lot of horizontal information,
so we are changing it to use the fluid layout all the time,
regardless of user preferences.

Changelog: changed

app/views/projects/pipelines/show.html.haml

+- @force_fluid_layout = true
 - add_to_breadcrumbs _('Pipelines'), project_pipelines_path(@project)
 - breadcrumb_title "##{@pipeline.id}"
 - page_title _('Pipeline')