This reverts merge request !40175

Upgrades the packags and removes unnecessary margins from search boxes
now that the margin is set in GitLab UI

Credit goes to: @mrincon

Apparently in version 8.3.0 the implementation for whatwg-url changed
which breaks our test. We probably should deal with this in a follow-up.

Also updates all jest related dependencies to be compatible with
jest@26.

Earlier versions of jest@26 had severe performance impacts, but that has
been resolved with jest@26.5. [0]

Thanks to this update `jest-environment-jsdom-sixteen` can be replaced
with the upstream `"jest-environment-jsdom` which is also based on
jsdom@16.

[0]: https://github.com/facebook/jest/issues/9457#issuecomment-703525151

to support Node.js 14, the upcoming Node LTS

Signed-off-by: Takuya Noguchi <takninnovationresearch@gmail.com>

Update qa/ Gemfile to match main activesupport

Also have to fix parallel in Gemfile.lock as that did not match the
Gemfile

Update rails/actioncable to match rails version number

https://github.com/rails/rails/blob/6-0-stable/actioncable/CHANGELOG.md

Remove jquery-ujs and use rails-ujs instead

Update gitlab ui and update snapshots from new gl-button prop.

Replaced gray-matter with a smaller in size
approach. We still leverage js-yaml to get
the parsing we're after, but we do so
without the added burden of gray-matter.
This additionally lets us use the same
js-yaml version across the codebase.

This adds the webvitals library to the performance bar mode