dashboard: change count of host-windows11-arm64-azure machines

Change-Id: I7cd3e57811aa1ee8385a02ee90f5be91948cb7c7
Reviewed-on: https://go-review.googlesource.com/c/build/+/464816
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>
Auto-Submit: Carlos Amedee <[email protected]>
Run-TryBot: Carlos Amedee <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: cagedmantis

dashboard/builders.go

@@ -556,7 +556,7 @@ var Hosts = map[string]*HostConfig{
 		Notes:     "Azure windows 11 arm64 VMs",
 		HostArch:  "windows-arm64",
 		IsReverse: true,
-		ExpectNum: 5,
+		ExpectNum: 2,
 	},
 }