tests: unify qemu binary paths for all qemu related tests

Our test data used a lot of different qemu binary paths and some
of them were based on downstream systems.

Note that there is one file where I had to add "accel=kvm" because
the qemuargv2xml code parses "/usr/bin/kvm" as virt type="kvm".

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>

tests/qemuargv2xmldata/qemuargv2xml-disk-drive-cache-unsafe.args

@@ -4,7 +4,7 @@ HOME=/home/test \
 USER=test \
 LOGNAME=test \
 QEMU_AUDIO_DRV=none \
-/usr/bin/qemu \
+/usr/bin/qemu-system-i686 \
 -name QEMUGuest1 \
 -S \
 -M pc \