Use Gitlab-Workhorse-Send-Data to send entry:

Closes #19224, Closes #19128

Also requires this MR to work:
https://gitlab.com/gitlab-org/gitlab-workhorse/merge_requests/53

app/controllers/projects/artifacts_controller.rb

@@ -23,8 +23,7 @@ class Projects::ArtifactsController < Projects::ApplicationController
     entry = build.artifacts_metadata_entry(params[:path])
     if entry.exists?
-      render json: { archive: build.artifacts_file.path,
-                     entry: Base64.encode64(entry.path) }
+      send_artifacts_entry(build, entry)
     else
       render json: {}, status: 404
     end

app/helpers/workhorse_helper.rb

@@ -21,4 +21,10 @@ module WorkhorseHelper
     headers.store(*Gitlab::Workhorse.send_git_archive(repository, ref: ref, format: format))
     head :ok
   end
+
+  # Send an entry from artifacts through Workhorse
+  def send_artifacts_entry(build, entry)
+    headers.store(*Gitlab::Workhorse.send_artifacts_entry(build, entry))
+    head :ok
+  end
 end

lib/gitlab/workhorse.rb

@@ -65,6 +65,18 @@ module Gitlab
         ]
       end
+      def send_artifacts_entry(build, entry)
+        params = {
+          'Archive' => build.artifacts_file.path,
+          'Entry' => Base64.encode64(entry.path)
+        }
+
+        [
+          SEND_DATA_HEADER,
+          "artifacts-entry:#{encode(params)}"
+        ]
+      end
+
       protected
       def encode(hash)