Fix an overwrite bug in the gcs metrics concern

When writing the gcs signed url metrics don't overwrite the existing
value if there is one. Now, we're going to merge the metrics into the
existing value.

Changelog: fixed

app/uploaders/packages/gcs_signed_url_metadata.rb

@@ -19,7 +19,7 @@ def url(*args, **kwargs)
         'x-goog-custom-audit-gitlab-size-bytes' => model.try(:size) || size
       }.compact.transform_values(&:to_s)
 
-      super(*args, **kwargs.merge(query: metadata_params))
+      super(*args, **kwargs.deep_merge(query: metadata_params))
     rescue StandardError => e
       Gitlab::ErrorTracking.track_exception(
         e,

spec/requests/projects/packages/package_files_controller_spec.rb

@@ -25,6 +25,36 @@
         .to eq(%(attachment; filename="#{filename}"; filename*=UTF-8''#{filename}))
     end
 
+    context 'when the fog provider is Google and on .com', :saas do
+      let(:package_file) { create(:package_file, :object_storage, package: package, file_name: filename) }
+
+      before do
+        stub_package_file_object_storage(
+          config: Gitlab.config.packages.object_store.merge(connection: {
+            provider: 'Google',
+            google_storage_access_key_id: 'test-access-id',
+            google_storage_secret_access_key: 'secret'
+          }),
+          proxy_download: true
+        )
+      end
+
+      it 'send the correct headers' do
+        subject
+
+        command, encoded_params = response.headers[::Gitlab::Workhorse::SEND_DATA_HEADER].split(':')
+        params = Gitlab::Json.parse(Base64.urlsafe_decode64(encoded_params))
+
+        expect(command).to eq('send-url')
+        expect(params['URL']).to include(
+          %(response-content-disposition=attachment%3B%20filename%3D%22#{filename}),
+          'x-goog-custom-audit-gitlab-project',
+          'x-goog-custom-audit-gitlab-namespace',
+          'x-goog-custom-audit-gitlab-size-bytes'
+        )
+      end
+    end
+
     context 'when file name has directory structure' do
       let(:filename) { 'dir%2Ffile.zip' }