qemu: monitor: Use qemuMonitorJSONGetReply in conjunction with virJSONValueArrayToStr...

qemu: monitor: Use qemuMonitorJSONGetReply in conjunction with virJSONValueArrayToStringList

In two instances (qemuMonitorJSONGetStringListProperty,
qemuMonitorJSONGetStringArray) the return value is checked by
qemuMonitorJSONCheckReply and extracted by
virJSONValueObjectGetStringArray.

We can use qemuMonitorJSONGetReply which returns it directly and then
virJSONValueArrayToStringList to convert it without the additional
lookup.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>