servo: Merge #19832 - Remove clean-cache from appveyor (from servo:jdm-patch-2); r=jdm

This fixes #19831.

Source-Repo: https://github.com/servo/servo
Source-Revision: 04aa53a94402919711ef86362f4c4d91a9ae6070

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 87db6a82399c3e330c0ab0c8a83501ff375610b8

servo/appveyor.yml

@@ -59,9 +59,7 @@ install:
 #  - ps: $blockRdp = $true; iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/appveyor/ci/master/scripts/enable-rdp.ps1'))
 
 build_script:
-  - set CARGO_HOME=C:\Users\appveyor\.cargo
   - mach clean-nightlies --keep 2 --force
-  - mach clean-cargo-cache --keep 2 --force
   - mach build -d -v
   - mach test-unit