[ci skip]

Moved TeamCity changelog entry to 8.7.3

See merge request !4049

[ci skip]

Log to application.log when an admin starts and stops impersonating a user

Closes gitlab-org/gitlab-ee#536

See merge request !4028

Use new build badge URLs

Use new build badge URLs to follow the instruction at [the project badges](https://gitlab.com/gitlab-org/gitlab-ce/badges).

See merge request !4037

Merge request widget displays TeamCity build state and code coverage correctly again

## What does this MR do?
This MR contains a fix for a regression introduced in `8.7`. In former version, the TeamCity build status was always displayed correctly. In `8.7` the build state is still checked, but the UI is not updated correctly any longer.

## Are there points in the code the reviewer needs to double check?
The changes are quite simple, so please simply double check them.

## Why was this MR needed?
This MR is needed to make the TeamCity build status working again.

## What are the relevant issue numbers?
#17080 

See merge request !3998

Use `number_to_human_size` helper to show repository size

This will intelligently format large repository sizes in GBs (or,
shudder, TBs).

Also, removes `rescue` clause from `repository_size` helper.
The repository size has since become calculated (and cached)
more intelligently, and this should no longer be necessary.

See merge request !4047

The repository size has since become calculated (and cached) more
intelligently, and this should no longer be necessary.