Use preinstalled Yarn on Appveyor

[thymikee]

Summary

Based on https://yarnpkg.com/lang/en/docs/install-ci/#appveyor-tab AppVeyor should have Yarn preinstalled. This should speedup the builds.

Test plan

AppVeyor green

[codecov-io]

Codecov Report

Merging #5548 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #5548   +/-   ##
=======================================
  Coverage   61.71%   61.71%           
=======================================
  Files         213      213           
  Lines        7149     7149           
  Branches        4        4           
=======================================
  Hits         4412     4412           
  Misses       2736     2736           
  Partials        1        1

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 133a9a1...ae96c17. Read the comment docs.

[rickhanlonii]

Works great

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
Please note this issue tracker is not a help forum. We recommend using StackOverflow or our discord channel for questions.