dashboard: set netbsd-arm{,64} builders to 0 expected

These are LUCI now. The buildlets won't come back.

Part of golang/go#63698.

Change-Id: I7e8fb2f1892d2f9e81e69a101e26072c4dd08788
Reviewed-on: https://go-review.googlesource.com/c/build/+/624875
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

dashboard/builders.go

@@ -467,12 +467,12 @@ var Hosts = map[string]*HostConfig{
 	},
 	"host-netbsd-arm-bsiegert": {
 		IsReverse: true,
-		ExpectNum: 1,
+		ExpectNum: 0, // was 1 before migration to LUCI
 		Owners:    []*gophers.Person{gh("bsiegert")},
 	},
 	"host-netbsd-arm64-bsiegert": {
 		IsReverse: true,
-		ExpectNum: 1,
+		ExpectNum: 0, // was 1 before migration to LUCI
 		Owners:    []*gophers.Person{gh("bsiegert")},
 	},
 	"host-openbsd-386-72": {