Merge prometheus unicorn sampler settigns within monitoring settings

config/gitlab.yml.example

@@ -543,14 +543,12 @@ production: &base
     #   enabled: true
     #   host: localhost
     #   port: 3808
-  prometheus:
-    # Time between sampling of unicorn socket metrics, in seconds
-    # unicorn_sampler_interval: 10
-
 
   ## Monitoring
   # Built in monitoring settings
   monitoring:
+    # Time between sampling of unicorn socket metrics, in seconds
+    # unicorn_sampler_interval: 10
     # IP whitelist to access monitoring endpoints
     ip_whitelist:
       - 127.0.0.0/8

config/initializers/1_settings.rb

@@ -499,12 +499,7 @@ Settings.webpack.dev_server['port']    ||= 3808
 #
 Settings['monitoring'] ||= Settingslogic.new({})
 Settings.monitoring['ip_whitelist'] ||= ['127.0.0.1/8']
-
-#
-# Prometheus metrics settings
-#
-Settings['prometheus'] ||= Settingslogic.new({})
-Settings.prometheus['unicorn_sampler_interval'] ||= 10
+Settings.monitoring['unicorn_sampler_interval'] ||= 10
 
 #
 # Testing settings

config/initializers/8_metrics.rb

@@ -119,7 +119,7 @@ def instrument_classes(instrumentation)
 end
 # rubocop:enable Metrics/AbcSize
 
-Gitlab::Metrics::UnicornSampler.initialize_instance(Settings.prometheus.unicorn_sampler_interval).start
+Gitlab::Metrics::UnicornSampler.initialize_instance(Settings.monitoring.unicorn_sampler_interval).start
 
 Gitlab::Application.configure do |config|
   # 0 should be Sentry to catch errors in this middleware