Added check and cleanup for storage/filecache
Added check and cleanup for storage/filecache

Some tests don't clean up the file cache and sometimes entries are
reused by mistake in subsequent test suites.

This cleans up the file cache and storage after every test suite and
also shows an annoying warning.

pollopolea/core,nextcloud/server,bluelml/core,bluelml/core,xx621998xx/server,pollopolea/core,Ardinis/server,Ardinis/server,cernbox/core,michaelletzgus/nextcloud-server,xx621998xx/server,pmattern/server,IljaN/core,bluelml/core,whitekiba/server,pmattern/server,endsguy/server,IljaN/core,xx621998xx/server,owncloud/core,endsguy/server,nextcloud/server,michaelletzgus/nextcloud-server,andreas-p/nextcloud-server,cernbox/core,xx621998xx/server,lrytz/core,jbicha/server,sharidas/core,andreas-p/nextcloud-server,lrytz/core,sharidas/core,pollopolea/core,whitekiba/server,IljaN/core,whitekiba/server,nextcloud/server,pmattern/server,pollopolea/core,sharidas/core,jbicha/server,Ardinis/server,lrytz/core,owncloud/core,IljaN/core,phil-davis/core,andreas-p/nextcloud-server,Ardinis/server,pixelipo/server,nextcloud/server,michaelletzgus/nextcloud-server,sharidas/core,whitekiba/server,lrytz/core,pmattern/server,lrytz/core,bluelml/core,owncloud/core,pixelipo/server,pixelipo/server,pixelipo/server,sharidas/core,pollopolea/core,jbicha/server,michaelletzgus/nextcloud-server,andreas-p/nextcloud-server,owncloud/core,bluelml/core,whitekiba/server,cernbox/core,endsguy/server,jbicha/server,IljaN/core,xx621998xx/server,endsguy/server,endsguy/server,jbicha/server,pmattern/server,andreas-p/nextcloud-server,cernbox/core,owncloud/core,pixelipo/server,cernbox/core,Ardinis/server