Change node memory query to use `max`

The metric name was changed in Omnibus to reflect
that we now take the max, not avg.

Also rename helper to indicate that we don't always take
the average anymore.

lib/gitlab/usage_data/topology.rb

@@ -51,7 +51,7 @@ module Gitlab
 
       def topology_app_requests_per_hour(client)
         result = query_safely('gitlab_usage_ping:ops:rate5m', 'app_requests', fallback: nil) do |query|
-          client.query(one_week_average(query)).first
+          client.query(aggregate_one_week(query)).first
         end
 
         return unless result
@@ -84,14 +84,14 @@ module Gitlab
       end
 
       def topology_node_memory(client)
-        query_safely('gitlab_usage_ping:node_memory_total_bytes:avg', 'node_memory', fallback: {}) do |query|
-          aggregate_by_instance(client, one_week_average(query))
+        query_safely('gitlab_usage_ping:node_memory_total_bytes:max', 'node_memory', fallback: {}) do |query|
+          aggregate_by_instance(client, aggregate_one_week(query, aggregation: :max))
         end
       end
 
       def topology_node_cpus(client)
         query_safely('gitlab_usage_ping:node_cpus:count', 'node_cpus', fallback: {}) do |query|
-          aggregate_by_instance(client, one_week_average(query, aggregation: :max))
+          aggregate_by_instance(client, aggregate_one_week(query, aggregation: :max))
         end
       end
 
@@ -114,25 +114,25 @@ module Gitlab
       def topology_service_memory_rss(client)
         query_safely(
           'gitlab_usage_ping:node_service_process_resident_memory_bytes:avg', 'service_rss', fallback: {}
-        ) { |query| aggregate_by_labels(client, one_week_average(query)) }
+        ) { |query| aggregate_by_labels(client, aggregate_one_week(query)) }
       end
 
       def topology_service_memory_uss(client)
         query_safely(
           'gitlab_usage_ping:node_service_process_unique_memory_bytes:avg', 'service_uss', fallback: {}
-        ) { |query| aggregate_by_labels(client, one_week_average(query)) }
+        ) { |query| aggregate_by_labels(client, aggregate_one_week(query)) }
       end
 
       def topology_service_memory_pss(client)
         query_safely(
           'gitlab_usage_ping:node_service_process_proportional_memory_bytes:avg', 'service_pss', fallback: {}
-        ) { |query| aggregate_by_labels(client, one_week_average(query)) }
+        ) { |query| aggregate_by_labels(client, aggregate_one_week(query)) }
       end
 
       def topology_all_service_process_count(client)
         query_safely(
           'gitlab_usage_ping:node_service_process:count', 'service_process_count', fallback: {}
-        ) { |query| aggregate_by_labels(client, one_week_average(query)) }
+        ) { |query| aggregate_by_labels(client, aggregate_one_week(query)) }
       end
 
       def topology_all_service_server_types(client)
@@ -228,7 +228,7 @@ module Gitlab
         end
       end
 
-      def one_week_average(query, aggregation: :avg)
+      def aggregate_one_week(query, aggregation: :avg)
         "#{aggregation}_over_time (#{query}[1w])"
       end