[ci] Speed up by fixing the nix instalation in ubuntu containers

Author: engdoreis

.github/workflows/ci.yml

@@ -89,18 +89,9 @@ jobs:
     steps:
       - uses: actions/checkout@v5
 
-       # This step is a workaround and should be removed when the container is fixed.
-      - name: Uninstall Nix
-        run: |
-          sudo rm -rf /etc/nix /etc/profile.d/nix.sh /etc/tmpfiles.d/nix-daemon.conf \
-          /nix ~root/.nix-channels ~root/.nix-defexpr ~root/.nix-profile ~root/.cache/nix
-
       - name: Install Nix
-        uses: cachix/install-nix-action@v27
-        with:
-          extra_nix_config: |
-            substituters = https://nix-cache.lowrisc.org/public/ https://cache.nixos.org/
-            trusted-public-keys = nix-cache.lowrisc.org-public-1:O6JLD0yXzaJDPiQW1meVu32JIDViuaPtGDfjlOopU7o= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
+        run: |
+          sudo chown -R $(whoami) /nix
 
       - name: Hash Bitstream
         id: hash-bitstream
@@ -122,22 +113,13 @@ jobs:
 
   fpga-test:
     runs-on: ["self-hosted", "ubuntu-22.04-fpga", "genesys2"]
-    needs: fpga-build 
+    # needs: fpga-build 
     steps:
       - uses: actions/checkout@v5
 
-       # This step is a workaround and should be removed when the container is fixed.
-      - name: Uninstall Nix
-        run: |
-          sudo rm -rf /etc/nix /etc/profile.d/nix.sh /etc/tmpfiles.d/nix-daemon.conf \
-          /nix ~root/.nix-channels ~root/.nix-defexpr ~root/.nix-profile ~root/.cache/nix
-
       - name: Install Nix
-        uses: cachix/install-nix-action@v27
-        with:
-          extra_nix_config: |
-            substituters = https://nix-cache.lowrisc.org/public/ https://cache.nixos.org/
-            trusted-public-keys = nix-cache.lowrisc.org-public-1:O6JLD0yXzaJDPiQW1meVu32JIDViuaPtGDfjlOopU7o= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
+        run: |
+          sudo chown -R $(whoami) /nix
 
       - uses: actions/cache@v5
         with: