functional: reduce number of replaced units for tests
functional: reduce number of replaced units for tests

Reduce number of units to be replaced during functional tests.
For submit it's still 9, but for load it becomes 6, and for start it
becomes 3. This is necessary for reducing time spent during functional
tests.

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