title: Multiple VPC static default route & selection criteria
body: <p>I'm trying to deploy a routing design that allows for VPC traffic to egress through a 3rd party virtual firewall so I employ security inspection (IPS, ect).</p>
  
  <p>I can easily set this up wit a single Firewall VM, adding a static default route pointing towards the Firewall VMs interface, and traffic flows through the VM as expected.</p>
  
  <p>To survive a zonal failure, I'd like to add a second firewall and an accompanying second default route pointing towards it with a routing higher metric.</p>
  
  <p>When I power down firewall VM #1, the GCP VPC Route UI indicates that the original route to VM#1 has issues (orange triangle) because the next-hop IP isn't available. But... the second default route (with a higher metric) doesn't replace the old route, so traffic won't forward to my second firewall VM.</p>
  
  <p>Is there a way to have a route pulled when the route is no longer healthy, allowing higher priority routes to take effect?</p>