Fix specs for active record

spec/lib/gitlab/metrics/subscribers/active_record_spec.rb

@@ -74,7 +74,8 @@ RSpec.describe Gitlab::Metrics::Subscribers::ActiveRecord do
         expect(subscriber).to receive(:current_transaction)
                                 .at_least(:once)
                                 .and_return(transaction)
-        expect(described_class.send(:gitlab_sql_duration_seconds)).to receive(:observe).with({}, 0.002)
+        expect(transaction).to receive(:observe).with(:gitlab_sql_duration_seconds, 0.002)
+
         subscriber.sql(event)
       end