DEV: Drop `logging_provider` site setting (#27785)

This site setting has always been experimental and hidden since it was
added 7 years ago. Drop it to simplify the way we enable logging in a
logstash friendly way.

config/initializers/101-lograge.rb

@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
-if (Rails.env.production? && SiteSetting.logging_provider == "lograge") ||
-     (ENV["ENABLE_LOGRAGE"] == "1")
+if ENV["ENABLE_LOGSTASH_LOGGER"] == "1"
   require "lograge"
 
   Rails.application.config.after_initialize do
@@ -144,29 +143,25 @@ if (Rails.env.production? && SiteSetting.logging_provider == "lograge") ||
           end
         end
 
-      if ENV["ENABLE_LOGSTASH_LOGGER"] == "1"
-        config.lograge.formatter = Lograge::Formatters::Logstash.new
+      config.lograge.formatter = Lograge::Formatters::Logstash.new
 
-        require "discourse_logstash_logger"
+      require "discourse_logstash_logger"
 
-        config.lograge.logger =
-          DiscourseLogstashLogger.logger(
-            logdev: Rails.root.join("log", "#{Rails.env}.log"),
-            type: :rails,
-            customize_event:
-              lambda do |event|
-                event["database"] = RailsMultisite::ConnectionManagement.current_db
-              end,
-          )
-
-        # Stop broadcasting to Rails' default logger
-        Rails.logger.stop_broadcasting_to(
-          Rails.logger.broadcasts.find { |logger| logger.is_a?(ActiveSupport::Logger) },
+      config.lograge.logger =
+        DiscourseLogstashLogger.logger(
+          logdev: Rails.root.join("log", "#{Rails.env}.log"),
+          type: :rails,
+          customize_event:
+            lambda { |event| event["database"] = RailsMultisite::ConnectionManagement.current_db },
         )
 
-        Logster.logger.subscribe do |severity, message, progname, opts, &block|
-          config.lograge.logger.add_with_opts(severity, message, progname, opts, &block)
-        end
+      # Stop broadcasting to Rails' default logger
+      Rails.logger.stop_broadcasting_to(
+        Rails.logger.broadcasts.find { |logger| logger.is_a?(ActiveSupport::Logger) },
+      )
+
+      Logster.logger.subscribe do |severity, message, progname, opts, &block|
+        config.lograge.logger.add_with_opts(severity, message, progname, opts, &block)
       end
     end
   end

config/site_settings.yml

@@ -2346,13 +2346,6 @@ developer:
   bypass_wizard_check:
     default: false
     hidden: true
-  logging_provider:
-    hidden: true
-    default: "default"
-    type: "list"
-    choices:
-      - "default"
-      - "lograge"
   bootstrap_error_pages:
     hidden: true
     default: false

db/migrate/20240709015048_remove_logging_provider_site_setting.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class RemoveLoggingProviderSiteSetting < ActiveRecord::Migration[7.1]
+  def up
+    execute "DELETE FROM site_settings WHERE name = 'logging_provider'"
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end