make-flight: reorganize scheduling related test jobs

make-flight: reorganize scheduling related test jobs

Scheduling related tests are ok to run on ARM, so do
not cut them off. They also do not depend on a
particular Dom0 architecture.

The net effect is that the following tests are removed:
 test-amd64-i386-xl-credit2
 test-amd64-i386-xl-multivcpu

while the following new ones are created:
 test-amd64-amd64-xl-credit2
 test-amd64-amd64-xl-multivcpu
 test-armhf-armhf-xl-credit2
 test-armhf-armhf-xl-multivcpu
 test-armhf-armhf-xl-sedf
 test-armhf-armhf-xl-sedf-pin

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>