another try

.github/workflows/linux_builds.yml

@@ -140,19 +140,18 @@ jobs:
           python-version: 3.8
           scons-version: 4.0
 
+      - name: Force remove preinstalled .NET SDKs
+        if: matrix.build-mono
+        run: |
+          sudo rm -rf /usr/share/dotnet/sdk/*
+
       - name: Setup older .NET SDK as baseline
         if: matrix.build-mono
         uses: actions/setup-dotnet@v4
         with:
           # Targeting the oldest version we want to support to ensure it still builds.
           dotnet-version: '8.0.111'
 
-      - name: Configure older .NET SDK version as the global version
-        if: matrix.build-mono
-        run: |
-          echo '{"sdk":{"version": "${{ steps.stepid.outputs.dotnet-version }}", "rollForward": "disable"}}' > global.json
-          cp global.json modules/mono/global.json
-
       - name: Compilation
         uses: ./.github/actions/godot-build
         with:
@@ -208,8 +207,6 @@ jobs:
         if: matrix.build-mono
         run: |
           dotnet test modules/mono/editor/Godot.NET.Sdk/Godot.SourceGenerators.Tests
-          # Undo global.json changes so they don't clash with class ref checks.
-          git checkout modules/mono/global.json
 
       # Check class reference
       - name: Check for class reference updates