integration: Fix TestGetContainersExport

The tar changes made the name of the file in the tar archive
change from  "./test" to "test", update the test to the new name.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)

integration/api_test.go

@@ -374,7 +374,7 @@ func TestGetContainersExport(t *testing.T) {
 			}
 			t.Fatal(err)
 		}
-		if h.Name == "./test" {
+		if h.Name == "test" {
 			found = true
 			break
 		}