Auto merge of #20095 - servo:jdm-patch-9, r=jdm

Set CARGO_HOME for Windows builders.

This is a temporary fix to allow reopening the tree. This value belongs in saltfs instead, but it's already late and I don't want to have to wait to deploy the changes.

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etc/ci/buildbot_steps.yml

@@ -189,6 +189,9 @@ arm64:
   - bash ./etc/ci/manifest_changed.sh
 
 windows-msvc-dev:
+  env:
+    CARGO_HOME: C:\buildbot\.cargo
+  commands:
   - mach.bat clean-cargo-cache --keep 3 --force
   - mach.bat clean-nightlies --keep 3 --force
   - mach.bat build --dev
@@ -198,6 +201,9 @@ windows-msvc-dev:
   - mach.bat test-stylo
 
 windows-msvc-nightly:
+  env:
+    CARGO_HOME: C:\buildbot\.cargo
+  commands:
   - mach.bat clean-cargo-cache --keep 3 --force
   - mach.bat clean-nightlies --keep 3 --force
   - mach.bat build --release