[canvaskit] Specify gold url and bucket for uploading

A previous change to goldctl removed the special-casing for
Skia, so we need to specify it ourselves.

Change-Id: If4d122daa4ee4bb865b628b7c6ee1cbe5d44d670
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/409396
Reviewed-by: Ravi Mistry <rmistry@google.com>

infra/bots/task_drivers/fm_driver/fm_driver.go

@@ -251,7 +251,7 @@ func main() {
 
 			// Only rerun sources from a batch (or we'd rerun failures over and over and over).
 			if len(sources) > 1 {
-				for name, _ := range reruns {
+				for name := range reruns {
 					failures += worker(ctx, []string{name}, flags)
 				}
 				return

infra/bots/task_drivers/run_wasm_gm_tests/run_wasm_gm_tests.go

@@ -140,7 +140,7 @@ func setupGoldctl(ctx context.Context, local bool, gitCommit, gerritCLID, tryjob
 
 	args = []string{
 		goldctlPath, "imgtest", "init", "--work-dir", workPath, "--instance", "skia", "--corpus", "gm",
-		"--commit", gitCommit,
+		"--commit", gitCommit, "--url", "https://gold.skia.org", "--bucket", "skia-infra-gm",
 	}
 	if gerritCLID != "" {
 		ps := strconv.Itoa(psOrder)