GHA/windows: add workaround for upstream vcpkg issue

Fixes:
```
error: https://github.com/google/brotli/archive/v1.1.0.tar.gz: WinHttpSendRequest failed with exit code 10106
```

Apply workaround:
https://github.com/microsoft/vcpkg/issues/41199#issuecomment-2378255699

Bug commit: d3fc35774f (diff-33cf7c311a76d4a838f91b078c2f8cbc984557379f7b345a268ec6deb665a91eR666-R675)
Fix commit: 3122da72b1
Fix PR: https://github.com/microsoft/vcpkg-tool/pull/1501

Fixes #15128
Reported-by: Viktor Szakats
Closes #15133

.github/workflows/windows.yml

@@ -729,7 +729,12 @@ jobs:
 
       - name: 'vcpkg build'
         timeout-minutes: 35
-        run: vcpkg x-set-installed ${{ matrix.install }} '--triplet=${{ matrix.arch }}-${{ matrix.plat }}'
+        run: |
+          # Temporary workaround pending: https://github.com/microsoft/vcpkg-tool/pull/1501
+          export SystemDrive="$SYSTEMDRIVE"
+          export SystemRoot="$SYSTEMROOT"
+          export windir="$WINDIR"
+          vcpkg x-set-installed ${{ matrix.install }} '--triplet=${{ matrix.arch }}-${{ matrix.plat }}'
 
       - name: 'cmake configure'
         timeout-minutes: 5