dashboard: reconfigure host counts for darwin amd64 builders

This change updates the desired host counts for darwin amd64 hosts.
The numbers require changing because:
- Migration to the new cluster with diffrent counts for amd64
machines.
- The addition of macOS 11.0 builders.

Updates golang/go#40762

Change-Id: I4a0dfcc8bd812ede38acbb98c0b317e03059b525
Reviewed-on: https://go-review.googlesource.com/c/build/+/307474
Trust: Carlos Amedee <carlos@golang.org>
Run-TryBot: Carlos Amedee <carlos@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/dashboard/builders.go b/dashboard/builders.go
index 7b1a285..8c3da86 100644
--- a/dashboard/builders.go
+++ b/dashboard/builders.go
@@ -465,7 +465,7 @@
 	},
 	"host-darwin-10_12": &HostConfig{
 		IsReverse: true,
-		ExpectNum: 5,
+		ExpectNum: 3,
 		Notes:     "MacStadium OS X 10.12 VM under VMWare ESXi",
 		env: []string{
 			"GOROOT_BOOTSTRAP=/Users/gopher/go1.4",
@@ -475,7 +475,7 @@
 	},
 	"host-darwin-10_14": &HostConfig{
 		IsReverse: true,
-		ExpectNum: 7,
+		ExpectNum: 3,
 		Notes:     "MacStadium macOS Mojave (10.14) VM under VMWare ESXi",
 		env: []string{
 			"GOROOT_BOOTSTRAP=/Users/gopher/goboot", // Go 1.12.1
@@ -485,7 +485,7 @@
 	},
 	"host-darwin-10_15": &HostConfig{
 		IsReverse: true,
-		ExpectNum: 7,
+		ExpectNum: 5,
 		Notes:     "MacStadium macOS Catalina (10.15) VM under VMWare ESXi",
 		env: []string{
 			"GOROOT_BOOTSTRAP=/Users/gopher/goboot", // Go 1.12.1
@@ -495,7 +495,7 @@
 	},
 	"host-darwin-amd64-11_0": &HostConfig{
 		IsReverse: true,
-		ExpectNum: 1,
+		ExpectNum: 5,
 		Notes:     "MacStadium macOS Big Sur (11.0) VM under VMWare ESXi",
 		env: []string{
 			"GOROOT_BOOTSTRAP=/Users/gopher/goboot", // Go 1.13.4
diff --git a/dashboard/builders_test.go b/dashboard/builders_test.go
index 15ee139..2de4779 100644
--- a/dashboard/builders_test.go
+++ b/dashboard/builders_test.go
@@ -877,8 +877,8 @@
 			got += config.ExpectNum
 		}
 	}
-	if got != 20 {
-		t.Fatalf("macstadium host count: got %d; want 20", got)
+	if got != 16 {
+		t.Fatalf("macstadium host count: got %d; want 16", got)
 	}
 }