functional-tests:clean: fix a typo in the functional-tests.log filename
functional-tests:clean: fix a typo in the functional-tests.log filename

functional-test.log should be functional-tests.log with (s)

dalbani/fleet,dalbani/fleet,giantswarm/fleet,dongsupark/fleet,coreos/fleet,improbable-io/fleet,endocode/fleet,coreos/fleet,giantswarm/fleet,dongsupark/fleet,jonboulle/fleet,improbable-io/fleet,improbable-io/fleet,dalbani/fleet,endocode/fleet,endocode/fleet,jonboulle/fleet,giantswarm/fleet,coreos/fleet,dongsupark/fleet,jonboulle/fleet