Add more descriptive message about NotImplementedError and display it in health check

app/models/geo_node_status.rb

@@ -6,6 +6,8 @@ class GeoNodeStatus
 
   def health
     @health ||= HealthCheck::Utils.process_checks(['geo'])
+  rescue NotImplementedError => e
+    @health = e.to_s
   end
 
   def healthy?

lib/gitlab/geo/health_check.rb

@@ -2,7 +2,7 @@ module Gitlab
   module Geo
     class HealthCheck
       def self.perform_checks
-        raise NotImplementedError unless Gitlab::Database.postgresql?
+        raise NotImplementedError.new('Geo is only compatible with PostgreSQL') unless Gitlab::Database.postgresql?
 
         return '' unless Gitlab::Geo.secondary?
         return 'The Geo secondary role is disabled.' unless Gitlab::Geo.secondary_role_enabled?