maximize disk space and enable cache env variables

.github/workflows/coverage.yml

@@ -9,11 +9,27 @@ on:
     branches:
       - 'polkadot-v1.10.0-coverage'
 
+env:
+  RUSTC_WRAPPER: sccache
+  SCCACHE_GHA_ENABLED: 'true'
+
 jobs:
   coverage:
     runs-on: ubuntu-latest
     name: Code Coverage
     steps:
+      # The build artifacts generated by Polkadot projects are already large
+      # and even larger when using llvm-cov. This GH task helps removing some large
+      # files on the host and maximizing disk space(https://github.com/easimon/maximize-build-space)
+      - name: Maximize build space
+        uses: easimon/maximize-build-space@master
+        with:
+          root-reserve-mb: 512
+          swap-size-mb: 1024
+          remove-dotnet: 'true'
+          remove-android: 'true'
+          remove-haskell: 'true'
+
       - uses: actions/checkout@v4
         with:
           submodules: true