Use FileStoreMounter in PipelineArtifact

This MR uses our new concern which extracts the logic
to update the file store column after record creation.

app/models/ci/pipeline_artifact.rb

@@ -6,6 +6,7 @@ module Ci
   class PipelineArtifact < ApplicationRecord
     extend Gitlab::Ci::Model
     include Artifactable
+    include FileStoreMounter
 
     FILE_STORE_SUPPORTED = [
       ObjectStorage::Store::LOCAL,
@@ -22,9 +23,8 @@ module Ci
     validates :size, presence: true, numericality: { less_than_or_equal_to: FILE_SIZE_LIMIT }
     validates :file_type, presence: true
 
-    mount_uploader :file, Ci::PipelineArtifactUploader
+    mount_file_store_uploader Ci::PipelineArtifactUploader
     before_save :set_size, if: :file_changed?
-    after_save :update_file_store, if: :saved_change_to_file?
 
     enum file_type: {
       code_coverage: 1
@@ -33,11 +33,5 @@ module Ci
     def set_size
       self.size = file.size
     end
-
-    def update_file_store
-      # The file.object_store is set during `uploader.store!`
-      # which happens after object is inserted/updated
-      self.update_column(:file_store, file.object_store)
-    end
   end
 end

spec/models/ci/pipeline_artifact_spec.rb

@@ -66,10 +66,16 @@ RSpec.describe Ci::PipelineArtifact, type: :model do
     subject { create(:ci_pipeline_artifact) }
 
     context 'when existing object has local store' do
-      it 'is stored locally' do
-        expect(subject.file_store).to be(ObjectStorage::Store::LOCAL)
-        expect(subject.file).to be_file_storage
-        expect(subject.file.object_store).to eq(ObjectStorage::Store::LOCAL)
+      it_behaves_like 'mounted file in local store'
+    end
+
+    context 'when direct upload is enabled' do
+      before do
+        stub_artifacts_object_storage(Ci::PipelineArtifactUploader, direct_upload: true)
+      end
+
+      context 'when file is stored' do
+        it_behaves_like 'mounted file in object store'
       end
     end
   end