Remove feature flag for usage ping batch counter

- Was default on (true) on all environments
- Was well tested past 3 months not to cause any problems

lib/gitlab/utils/usage_data.rb

@@ -40,7 +40,7 @@ module Gitlab
       FALLBACK = -1
 
       def count(relation, column = nil, batch: true, start: nil, finish: nil)
-        if batch && Feature.enabled?(:usage_ping_batch_counter, default_enabled: true)
+        if batch
           Gitlab::Database::BatchCount.batch_count(relation, column, start: start, finish: finish)
         else
           relation.count
@@ -50,7 +50,7 @@ module Gitlab
       end
 
       def distinct_count(relation, column = nil, batch: true, batch_size: nil, start: nil, finish: nil)
-        if batch && Feature.enabled?(:usage_ping_batch_counter, default_enabled: true)
+        if batch
           Gitlab::Database::BatchCount.batch_distinct_count(relation, column, batch_size: batch_size, start: start, finish: finish)
         else
           relation.distinct_count_by(column)