Track execution of project overwrite service

What does this MR do?

This merge request adds tracking of Projects::OverwriteProjectService that is used by import/export feature.

This services creates a possibly long-running transaction creating multiple subtransaction through Project.transaction(requires_new: true).

It is possible that this might affect performance in multiple places, especially performance of the new CI/CD builds queuing queries.

For more details see gitlab-com/gl-infra/production#5152 (comment 629653355) and https://gitlab.com/gitlab-org/gitlab/-/issues/334638.

Conformity

• I have self-reviewed this MR per code review guidelines.
• This change is backwards compatible across updates.

app/services/projects/overwrite_project_service.rb

@@ -5,6 +5,8 @@ class OverwriteProjectService < BaseService
     def execute(source_project)
       return unless source_project && source_project.namespace == @project.namespace
 
+      start_time = ::Gitlab::Metrics::System.monotonic_time
+
       Project.transaction do
         move_before_destroy_relationships(source_project)
         # Reset is required in order to get the proper
@@ -25,10 +27,25 @@ def execute(source_project)
       else
         raise
       end
+
+    ensure
+      track_service(start_time, source_project, e)
     end
 
     private
 
+    def track_service(start_time, source_project, exception)
+      return if ::Feature.disabled?(:project_overwrite_service_tracking, source_project, default_enabled: :yaml)
+
+      duration = ::Gitlab::Metrics::System.monotonic_time - start_time
+
+      Gitlab::AppJsonLogger.info(class: self.class.name,
+                                 namespace_id: source_project.namespace.id,
+                                 project_id: source_project.id,
+                                 duration_s: duration.to_f,
+                                 error: exception.class.name)
+    end
+
     def move_before_destroy_relationships(source_project)
       options = { remove_remaining_elements: false }