fix: Configure CI to use Docker for go tests and add Docker availability checks to sandbox manager tests.

.github/workflows/pr.yml

@@ -41,3 +41,5 @@ jobs:
 
       - name: Run go test
         run: go test ./...
+        env:
+          DOCKER_HOST: unix:///var/run/docker.sock

pkg/agent/sandbox/manager_test.go

@@ -311,6 +311,9 @@ func TestScopedSandboxManager_Delegates(t *testing.T) {
 }
 
 func TestScopedSandboxManager_ContainerDelegates(t *testing.T) {
+	_, cleanup := skipIfNoDocker(t)
+	defer cleanup()
+
 	home := t.TempDir()
 	t.Setenv("HOME", home)
 	ws := filepath.Join(home, "container_ws")
@@ -379,6 +382,9 @@ func TestScopedSandboxManager_ContainerDelegates(t *testing.T) {
 }
 
 func TestScopedSandboxManager_ContainerCreationError(t *testing.T) {
+	_, cleanup := skipIfNoDocker(t)
+	defer cleanup()
+
 	home := t.TempDir()
 	t.Setenv("HOME", home)