Use commit deltas when counting files in IrkerWorker

CHANGELOG

@@ -57,7 +57,7 @@ v 8.11.0 (unreleased)
   - Sensible state specific default sort order for issues and merge requests !5453 (tomb0y)
   - Fix RequestProfiler::Middleware error when code is reloaded in development
   - Catch what warden might throw when profiling requests to re-throw it
-  - Speed up and reduce memory usage of Commit#repo_changes and Repository#expire_avatar_cache
+  - Speed up and reduce memory usage of Commit#repo_changes, Repository#expire_avatar_cache and IrkerWorker
 
 v 8.10.3
   - Fix Import/Export issue importing milestones and labels not associated properly. !5426

app/workers/irker_worker.rb

@@ -141,7 +141,7 @@ class IrkerWorker
   end
 
   def files_count(commit)
-    diffs = commit.raw_diffs
+    diffs = commit.raw_diffs(deltas_only: true)
 
     files = "#{diffs.real_size} file"
     files += 's' if diffs.size > 1