tests/sfreq/smoke_test: fix executor integration
tests/sfreq/smoke_test: fix executor integration

A recent refactoring of the executor class has broken this test since now
tests and experiments configuration have to be provided via two mandatory
attributes.

This patch fixes this test by using the new interface.

Signed-off-by: Patrick Bellasi <431c86f368affbc3148c4669fbd465131f7e82cb@arm.com>

ARM-software/lisa,joelagnel/lisa,arnoldlu/lisa,credp/lisa,credp/lisa,ARM-software/lisa,credp/lisa,arnoldlu/lisa,joelagnel/lisa,mdigiorgio/lisa,credp/lisa,bjackman/lisa,mdigiorgio/lisa,ARM-software/lisa,bjackman/lisa,ARM-software/lisa