tests: Refactors PodSandbox creation

Most of the tests creating and using Pod Sandboxes in the same way. We can create
a common function that will do that for us, so we can have less duplicated code,
and make it easier to add new tests in the future.

Signed-off-by: Claudiu Belu <cbelu@cloudbasesolutions.com>

integration/container_without_image_ref_test.go

@@ -27,13 +27,7 @@ import (
 // Test container lifecycle can work without image references.
 func TestContainerLifecycleWithoutImageRef(t *testing.T) {
 	t.Log("Create a sandbox")
-	sbConfig := PodSandboxConfig("sandbox", "container-lifecycle-without-image-ref")
-	sb, err := runtimeService.RunPodSandbox(sbConfig, *runtimeHandler)
-	require.NoError(t, err)
-	defer func() {
-		assert.NoError(t, runtimeService.StopPodSandbox(sb))
-		assert.NoError(t, runtimeService.RemovePodSandbox(sb))
-	}()
+	sb, sbConfig := PodSandboxConfigWithCleanup(t, "sandbox", "container-lifecycle-without-image-ref")
 
 	var (
 		testImage     = GetImage(BusyBox)