Mediawiki ui icons are 24x24 however should be 20x20.
Minerva currently overrides the entire stylesheet to achieve this.
Changes implemented in T177432 resulted in `.mw-ui-icon` contained icons being blurry and labels being really close.
{F16429549}
# Acceptance criteria
[] The stylesheet inside Minerva is made the default in core so that it applies Vector.
[] This should feature flagged to allow for testing in the beta cluster (either with new module or ResourceLoader magic) and allow us to deploy when we are ready to. It should be disabled by default.
[] We should remove the Minerva override once the default is in place
# Design review
- [] With user links disabled, verify the sidebar toggle icon meets current design specifications https://en.wikipedia.beta.wmflabs.org/wiki/Spain?useskinversion=2&vectoruserlinks=0
- [] Using modern Vector with userlinks enabled https://en.wikipedia.beta.wmflabs.org/wiki/Language_test?vectoruserlinks=1&useskinversion=2 verify that the language button on the beta cluster is consistent with the language button currently deployed in production.
- [] Using modern Vector with userlinks enabled https://en.wikipedia.beta.wmflabs.org/wiki/Language_test?vectoruserlinks=0&useskinversion=2 and ignoring the Echo icons, verify that the sidebar toggle, user toggle and associated menu items meet design specifications.
This can skip QA provided the designer is happy and move to sign off. If there is any value in QA the designer should add some suggested QA instructions. If there is any issues requiring follow up please ping @jdlrobson
NOTE: QA of icons impacted in page previews will be done as part of another task.