integration: remove deprecated endpoint test

`/containers/<name>/copy` endpoint was deprecated in 1.8 and errors
since 1.12. See https://github.com/moby/moby/pull/22149 for more info.

Signed-off-by: Roman Volosatovs <roman.volosatovs@docker.com>

integration/container/container_test.go

@@ -13,7 +13,6 @@ func TestContainerInvalidJSON(t *testing.T) {
 	defer setupTest(t)()
 
 	endpoints := []string{
-		"/containers/foobar/copy",
 		"/containers/foobar/exec",
 		"/exec/foobar/start",
 	}