Revert "Add Build seed specs"

This reverts commit 03bc722e.

Revert "Add build specs"

This reverts commit c2d49565.

Revert "Refactor parallelization implementation"

This reverts commit 72430483.

Revert "Implement POC for job parallelization"

This reverts commit 44b740f9.

* Move the variables to ::Ci::Build#predefined_variables
* Tweak pipeline build seed implementation

User not defined in PostReceive#process_project_changes

Closes #51335

See merge request gitlab-org/gitlab-ce!22519

Adds trace of each access check when git push times out

Closes #42790

See merge request gitlab-org/gitlab-ce!22265

Upgrade Prometheus to 2.4.3 and Alertmanager to 0.15.2

See merge request gitlab-org/gitlab-ce!22600

docs add first draft for runbook topic

See merge request gitlab-org/gitlab-ce!22588

# Conflicts:
#	doc/topics/runbooks/index.md

Update review apps testing guide

See merge request gitlab-org/gitlab-ce!22619

E2E Test - LDAP login with SSL

Closes gitlab-qa#59

See merge request gitlab-org/gitlab-ce!22574

Prettify all the things (part 4)

See merge request gitlab-org/gitlab-ce!22253

Resolve circular dependencies in merge request widget

See merge request gitlab-org/gitlab-ce!22605

Resolve "No longer require a deploy to start Prometheus monitoring"

Closes #45068

See merge request gitlab-org/gitlab-ce!22401

Review Apps are now deployed automatically.
Note that if auth fails you might need to stop and redeploy the app.

Feature/add license to project API

See merge request gitlab-org/gitlab-ce!21606

Update content of visible tooltips

See merge request gitlab-org/gitlab-ce!22504

CE: Put EE routes in EE files under EE directories

See merge request gitlab-org/gitlab-ce!22376

Automatically navigate to last board visited

See merge request gitlab-org/gitlab-ce!22430

Improvement to ci/yaml documentation

See merge request gitlab-org/gitlab-ce!22613

Resolve "Adding issues from group/project board is not allowed for project-level users"

See merge request gitlab-org/gitlab-ce!22557