Don't pull back all records when detecting metrics

This avoids `recs.to_a` and uses `recs.klass` instead

https://bugzilla.redhat.com/show_bug.cgi?id=1251259

app/models/metric/helper.rb

@@ -120,7 +120,11 @@ def self.sanitize_start_end_time(interval, interval_name, start_time, end_time)
  end
 
  def self.remove_duplicate_timestamps(recs)
- return recs if recs.empty? || !recs.all? { |r| r.kind_of?(Metric) || r.kind_of?(MetricRollup) }
+ if recs.respond_to?(:klass) # active record relation
+ return recs unless recs.klass.kind_of?(Metric) || recs.klass.kind_of?(MetricRollup)
+ elsif recs.empty? || !recs.all? { |r| r.kind_of?(Metric) || r.kind_of?(MetricRollup) }
+ return recs 
+ end
 
  recs = recs.sort_by { |r| r.resource_type + r.resource_id.to_s + r.timestamp.iso8601 }