tests: move all files' writes into loop
tests: move all files' writes into loop

jonboulle/fleet,giantswarm/fleet,endocode/fleet,dalbani/fleet,dalbani/fleet,jonboulle/fleet,dalbani/fleet,endocode/fleet,coreos/fleet,dongsupark/fleet,jonboulle/fleet,dongsupark/fleet,dongsupark/fleet,giantswarm/fleet,coreos/fleet,endocode/fleet,coreos/fleet,giantswarm/fleet