Save multi-dashboard logic for another MR

app/controllers/projects/environments_controller.rb

@@ -163,7 +163,7 @@ class Projects::EnvironmentsController < Projects::ApplicationController
 
     respond_to do |format|
       format.json do
-        dashboard = MetricsDashboardService.new(@project).find(params[:dashboard])
+        dashboard = MetricsDashboardService.new.get_dashboard
 
         render json: dashboard, status: :ok
       end

app/services/metrics_dashboard_service.rb

 # frozen_string_literal: true
 
-# Searches a projects repository for a metrics dashboard and formats the output.
-# Expects any custom dashboards will be located in `.gitlab/dashboards`
+# Fetches the metrics dashboard layout and supplemented the output with DB info.
 class MetricsDashboardService
-  DASHBOARD_ROOT = ".gitlab/dashboards"
-  DASHBOARD_EXTENSION = '.yml'
-
   SYSTEM_DASHBOARD_NAME = 'system_dashboard'
-  SYSTEM_DASHBOARD_ROOT = "config/prometheus"
-  SYSTEM_DASHBOARD_PATH = Rails.root.join(SYSTEM_DASHBOARD_ROOT, "#{SYSTEM_DASHBOARD_NAME}#{DASHBOARD_EXTENSION}")
-
-  def initialize(project)
-    @project = project
-  end
+  SYSTEM_DASHBOARD_PATH = Rails.root.join("config/prometheus", "#{SYSTEM_DASHBOARD_NAME}.yml")
 
   # Returns a DB-supplemented json representation of a dashboard config file.
-  #
-  # param: dashboard_name [String] Filename of dashboard w/o an extension.
-  #     If not provided, the system dashboard will be returned.
-  def find(dashboard_name = nil)
-    unless Feature.enabled?(:environment_metrics_show_multiple_dashboards, @project)
-      return process_dashboard(system_dashboard)
-    end
-
-    dashboard = Rails.cache.fetch(cache_key(dashboard_name)) do
-      dashboard_name ? project_dashboard(dashboard) : system_dashboard
-    end
+  def get_dashboard
+    dashboard = Rails.cache.fetch(cache_key) { system_dashboard }
 
     process_dashboard(dashboard)
   end
@@ -37,19 +19,8 @@ class MetricsDashboardService
     YAML.load_file(SYSTEM_DASHBOARD_PATH)
   end
 
-  # Searches the project repo for a custom-defined dashboard.
-  def project_dashboard(dashboard_name)
-    Gitlab::Template::Finders::RepoTemplateFinder.new(
-      project,
-      DASHBOARD_ROOT,
-      DASHBOARD_EXTENSION
-    ).find(dashboard_name).read
-  end
-
-  def cache_key(dashboard_name)
-    return "metrics_dashboard_#{SYSTEM_DASHBOARD_NAME}" unless dashboard_name
-
-    "project_#{@project.id}_metrics_dashboard_#{dashboard_name}"
+  def cache_key
+    "metrics_dashboard_#{SYSTEM_DASHBOARD_NAME}"
   end
 
   # TODO: "Processing" the dashboard needs to include several steps such as