Fix importer for GitHub Pull Requests when a branch was reused across Pull Requests

Closes #17766

## What does this MR do?

GitHub importer fails when a repository has two Pull Requests, with the same branch name and different SHA, one of which was closed without merging, and one which is open or was merged in. This happens because we only checks if the branch exists in the [Gitlab::GithubImport::BranchFormatter#exists?](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/lib/gitlab/github_import/branch_formatter.rb#L6-8), before creating the missing references on Github. With this MR we check if both branch, and SHA exists in the current project. If no, we create the missing reference on GitHub before import the PR.

## Are there points in the code the reviewer needs to double check?

Nope.

## Why was this MR needed?

Github importer will fail if branch was reused across Pull Requests.

## What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/19439

/cc @royaldark @thomasjachmann

See merge request !5103

Cancel creating or editing note by hitting Escape

/cc @rspeicher 

See merge request !5075

Remove duplicate templates that are lowercase

See merge request !5114

Throttle the update of `project.pushes_since_gc` to 1 minute

## What does this MR do?

Throttle the update of `project.pushes_since_gc` to alleviate DB load

## What are the relevant issue numbers?

Relates to #15094

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- ~~[ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- ~~[ ] API support added~~
- Tests
  - ~~[ ] Added for this feature/bug~~
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)


See merge request !5083

Signed-off-by: Rémy Coutable <remy@rymai.me>

Fix diff comments not showing up in activity feed

## What does this MR do?

It fixes the detection of note events to check for `Note` and `LegacyDiffNote`.

## Are there points in the code the reviewer needs to double check?

No? /cc @DouweM (since I believe you introduced `LegacyDiffNote`

## Why was this MR needed?

To fix #19092.

## What are the relevant issue numbers?

Fixes #19092.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5069

Bump GITLAB_SHELL_VERSION to 3.2.0

Bump GITLAB_SHELL_VERSION to 3.2.0

Needed for !4696 to properly work.

Blocked by gitlab-org/gitlab-shell!62

See merge request !5101

Allow `?`, or `&` for label names

Closes #18727 

See merge request !4724

Fixing URL validation for import_url on projects

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/17536

This MR fixes problems related to bypassing `import_url` validation on projects. This makes sure the URL is properly validated so we don't enter crap and fail while running workers that handle this URL.

It also adds a migration to fix current invalid `import_url`s

See merge request !4753

Signed-off-by: Rémy Coutable <remy@rymai.me>

Add and update .gitignore & .gitlab-ci.yml templates for 8.10



See merge request !5107

Add more debug info to import/export and memory killer

This should help debug https://gitlab.com/gitlab-org/gitlab-ce/issues/19124 further

See merge request !5108

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

Add setting that allows admins to choose which Git access protocols are enabled.

## What does this MR do?

It allows admins to disable one of the two protocols for Git access. They can choose to enable just SSH, HTTP or allow both. If one of them is disabled, the clone URL in the project will show only the allowed protocol, and no dropdown to change protocols will be presented.

## What are the relevant issue numbers?

Full implementation on GitLab's side for #18601 

GitLab Shell implementation: gitlab-org/gitlab-shell!62

GitLab Workhorse implementation: gitlab-org/gitlab-workhorse!51

## Screenshots (if relevant)

![Screen_Shot_2016-06-16_at_12.26.19_PM](/uploads/bad845142e9704a7385b2eaca51fd4eb/Screen_Shot_2016-06-16_at_12.26.19_PM.png)
![Screen_Shot_2016-06-20_at_4.24.54_PM](/uploads/6e452dd269e06f0be23841ce93866ed6/Screen_Shot_2016-06-20_at_4.24.54_PM.png)



/cc @jschatz1  this MR touches the UI. Please review.

See merge request !4696