Fix grammar and typos in Runners pages

_Originally opened at !1791 by @axil._

- - -

## Does this MR meet the acceptance criteria?

- [ ] [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
  - [ ] All builds are passing
- [ ] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !6547

This reverts merge request !6188

Fix permission for setting an issue's due date

## What does this MR do?

This merge request ensure the current user can `:admin_issue` in order to change the issue's `due_date`, in `BaseIssuableService` and in `SlashCommands::InterpretService`.

Closes #22592 

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

No.

## 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 [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] 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 !6539

Added tests

Added awesomeeeeee icons

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

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

Send ajax request for label update only if they are changed

## What does this MR do?

At the moment we send requests to update the labels on issue even if nothing has been changed. This fixes that and only sends requests when something has actually been changed.

The code gets the initial selected values based on the inputs & then compares that to the selected values when submitting. If they are equal, then no request is sent.

## What are the relevant issue numbers?

Closes #19472 

See merge request !5071

Add more tests for calendar contribution

## What does this MR do?
Add more tests for calendar contribution

## Are there points in the code the reviewer needs to double check?
Shouldn't be

## Why was this MR needed?
Improve test coverage for calendar

## Screenshots (if relevant)
None

## Does this MR meet the acceptance criteria?

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

## What are the relevant issue numbers?
Closes #22347

See merge request !6421

Fixed issue board label filtering not removing labels

## What does this MR do?

When trying to remove a label filter it would actually add it instead making it impossible to remove the label filter without modifying the URL. This fixes that by correctly removing the label from the filter.

## What are the relevant issue numbers?

Closes #21417

See merge request !6208