PHRAS-2494 keep node_modules directory for performance

Makefile

@@ -8,18 +8,15 @@ install_composer:
 	composer install --ignore-platform-reqs
 
 install_asset_dependencies:
-	yarn upgrade 
+	yarn install
 	./node_modules/.bin/gulp build
 
 install_assets:
 	./node_modules/.bin/gulp install-assets
 
 clean_assets:
-	rm -rf ./node_modules
 	rm -rf ./www/assets
 	rm -Rf ./cache/*
-	mkdir ./node_modules
-	touch ./node_modules/.gitkeep
 
 config:
 	@php bin/console compile:configuration