integration: remove unused constants and fields (unused)

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

integration/container/create_test.go

@@ -385,7 +385,6 @@ func TestCreateWithCustomReadonlyPaths(t *testing.T) {
 	ctx := context.Background()
 
 	testCases := []struct {
-		doc           string
 		readonlyPaths []string
 		expected      []string
 	}{

integration/image/remove_unix_test.go

@@ -88,6 +88,6 @@ func TestRemoveImageGarbageCollector(t *testing.T) {
 
 	// Run imageService.Cleanup() and make sure that layer was removed from disk
 	i.Cleanup()
-	dir, err = os.Stat(data["UpperDir"])
-	assert.ErrorContains(t, err, "no such file or directory")
+	_, err = os.Stat(data["UpperDir"])
+	assert.Assert(t, os.IsNotExist(err))
 }

integration/plugin/graphdriver/main_test.go

@@ -17,8 +17,6 @@ func init() {
 	reexec.Init() // This is required for external graphdriver tests
 }
 
-const dockerdBinary = "dockerd"
-
 func TestMain(m *testing.M) {
 	var err error
 	testEnv, err = environment.New()