pass availability zone to console during pageserver registration (#2991)

this is safe because unknown fields are ignored. After the corresponding PR in control plane is merged this field
is going to be required

Part of https://github.com/neondatabase/cloud/issues/3131

.github/ansible/scripts/init_pageserver.sh

@@ -1,7 +1,8 @@
 #!/bin/sh
 
-# get instance id from meta-data service
+# fetch params from meta-data service
 INSTANCE_ID=$(curl -s http://169.254.169.254/latest/meta-data/instance-id)
+AZ_ID=$(curl -s http://169.254.169.254/latest/meta-data/placement/availability-zone)
 
 # store fqdn hostname in var
 HOST=$(hostname -f)
@@ -16,7 +17,8 @@ cat <<EOF | tee /tmp/payload
   "instance_id": "${INSTANCE_ID}",
   "http_host": "${HOST}",
   "http_port": 9898,
-  "active": false
+  "active": false,
+  "availability_zone_id": "${AZ_ID}"
 }
 EOF