testsuite: Remove duplicate test

This partially reverts ad7f175 ("Add test for depmod using search dirs
with same prefix"). Testing it twice in the inverted order doesn't
ensure we get the bug with wrong ordering.

As put by Anssi Hannula <anssi@mageia.org>:

	So the bug is triggered only if the shorter name is higher-prio _and_
	shorter name is traversed first. If the long name is traversed first,
	the bug don't trigger with either "search" directive order (and on my
	"make check" runs this is the case).