Fixed issue with sidebar edit links toggling anchor
This caused an issue with the page scrolling from the bottom to the top. Also stopped the dropdown links doing the same.
See merge request !3819
Removed commented text from system notes

See merge request !3836
Fixed issue with new MR form layout
Currently it is all over the place:

Now:

See merge request !3837
Fixes issue with note form inheriting text color
It was only really noticeable on dark themed diffs

See merge request !3834
add slack notifications for wiki pages
## What does this MR do?
Lets the Slack service be configured to send notifications when wiki pages are created or edited.
## Are there points in the code the reviewer needs to double check?
I'm just starting to get familiar with the Gitlab codebase and I was unsure on how to get the wiki page url to pass it to the slack message, on whether or not I needed to refactor the create/update methods for wiki pages from the controller to a service (but seemed necessary to test it better), and if I needed to add a column to the web hooks table or if the services table would have been enough. Please let me know if I should change anything and I will improve the MR, thanks for checking :)
## Why was this MR needed?
Related to #563 and fixes#4233.
See merge request !2998
Add raw build trace output
Closes#15308, #15147
Changes in the UI:
- on finished build:

- on running build:

See merge request !3767