ci: make Spread tests use LXD and arm runners

.github/workflows/spread.yaml

@@ -6,8 +6,15 @@ on:
 
 jobs:
   spread-tests:
-    name: Run Spread tests
-    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        runner:
+          - name: X64
+            runs-on: ubuntu-latest
+          - name: ARM64
+            runs-on: [noble, ARM64, large]
+    name: Run Spread tests | ${{ matrix.runner.name }}
+    runs-on: ${{ matrix.runner.runs-on }}
     steps:
       - uses: actions/checkout@v4
 
@@ -38,13 +45,16 @@ jobs:
         with:
           go-version: '>=1.17.0'
 
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v3
+      - name: Install LXD
+        uses: canonical/[email protected]
+        with:
+            channel: 5.21/stable
 
       - name: Prepare Spread suites
         id: spread-suites
         env:
           integration-tests: "tests/spread/integration"
+          backend: "lxd"
         run: |
           set -ex
           spread_tasks=""
@@ -54,7 +64,7 @@ jobs:
             pkg_tests="${{ env.integration-tests }}/${pkg_name}"
             if [ -f "${pkg_tests}/task.yaml" ] && [[ $spread_tasks != *"${pkg_tests}"* ]]
             then
-              spread_tasks="${spread_tasks} ${pkg_tests}"
+              spread_tasks="${spread_tasks} ${{ env.backend }}:${pkg_tests}"
             fi
           done