Move Prometheus presentation logic to PrometheusText

+ Use NullMetrics to mock metrics when unused
+ Use method_missing in NullMetrics mocking
+ Update prometheus gem to version that correctly uses transitive dependencies
+ Ensure correct folders are used in Multiprocess prometheus client tests.
+ rename Sessions controller's metric

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/gitlab/metrics.rb b/lib/gitlab/metrics.rb
index a41cbd214a1..34f6b32f7da 100644
--- a/lib/gitlab/metrics.rb
+++ b/lib/gitlab/metrics.rb
@@ -73,7 +73,7 @@ module Gitlab
       if prometheus_metrics_enabled?
         registry.get(name)
       else
-        DummyMetric.new
+        NullMetric.new
       end
     end