(EE-Port) Allow maintainers to push forks of a project for branches that have open MRs

See merge request gitlab-org/gitlab-ee!4885

Since now we're setting the auhtor in the `MergeRequest::BuildService`

We now need to check if the user does not have access to the pipeline
through a merge request that allows maintainer access

When a project is not private, and the source branch not protected the
user can now select the option to allow maintainers to push to this
branch.

This flag will allow maintainers of a project to push to specific
branches of a fork of a project

Custom Metrics backend and UI for creating and editing queries

See merge request gitlab-org/gitlab-ee!3799

Geo - Repository verification on secondary node

See merge request gitlab-org/gitlab-ee!4749

Fix failure in ee/spec/services/ci_cd/github_setup_service_spec.rb

See merge request gitlab-org/gitlab-ee!4890

[EE] Don't delete todos or unassign issues and MRs when a user leaves a project

See merge request gitlab-org/gitlab-ee!4889

Geo - Calculate repositories checksum on primary node

Closes #4756

See merge request gitlab-org/gitlab-ee!4428

CI/CD only GitHub import sets up service integrations

Closes #4721

See merge request gitlab-org/gitlab-ee!4687

Merge branch '5174-spec-failure-ee-spec-finders-geo-lfs_object_registry_finder_spec-rb' into 'master'

Resolve "Spec failure: ee/spec/finders/geo/lfs_object_registry_finder_spec.rb"

Closes #5174

See merge request gitlab-org/gitlab-ee!4888

Sets up service to notify GitHub of pipeline status

Create CI/CD-only projects from GitHub

Closes #3839

See merge request gitlab-org/gitlab-ee!4688

CE upstream - 2018-03-07 17:11 UTC

Closes #5171

See merge request gitlab-org/gitlab-ee!4884

Resolve "User::DestroyService should cleanup projects where user is mirror_user"

Closes #3892

See merge request gitlab-org/gitlab-ee!4827

Move SidebarAssignees vue component

See merge request gitlab-org/gitlab-ee!4766

Resolve "Job Failed #56264107 and #56261601"

Closes #5171

See merge request gitlab-org/gitlab-ee!4887

- Remove unwanted chat was failing as a consequence of moving external support from Premium to starter. We have a dependency on config_processor a project with a repository must be used

Closes #5171

- Remove unwanted chat was failing as a consequence of moving external support from Premium to starter. We have a dependency on config_processor a project with a repository must be used

Closes #5171

owner who also gets notified of this change