dashboard: disable cmd/go tests on plan9-amd64-9front

The cmd/go tests are timing out on the plan9/amd64
builder because they take more than 20m to complete.

This change disables the cmd/go tests on the
plan9/amd64 builder, like it was done on the
plan9/386 builder.

Updates golang/go#31910.

Change-Id: I157b472da8498ddce0f641cccb79bc50ae65ca3b
Reviewed-on: https://go-review.googlesource.com/c/build/+/175898
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/dashboard/builders.go b/dashboard/builders.go
index 838da93..d7d1c9d 100644
--- a/dashboard/builders.go
+++ b/dashboard/builders.go
@@ -2179,11 +2179,21 @@
 		buildsRepo:        onlyMaster,
 	})
 	addBuilder(BuildConfig{
-		Name:              "plan9-amd64-9front",
-		HostType:          "host-plan9-amd64-0intro",
-		SkipSnapshot:      true,
-		shouldRunDistTest: noTestDir,
-		buildsRepo:        onlyMaster,
+		Name:         "plan9-amd64-9front",
+		HostType:     "host-plan9-amd64-0intro",
+		SkipSnapshot: true,
+		shouldRunDistTest: func(distTestName string, isTry bool) bool {
+			if !noTestDir(distTestName, isTry) {
+				return false
+			}
+			switch distTestName {
+			case "api",
+				"go_test:cmd/go": // takes over 20 minutes without working SMP
+				return false
+			}
+			return true
+		},
+		buildsRepo: onlyMaster,
 	})
 	addBuilder(BuildConfig{
 		Name:             "aix-ppc64",