testimage: symlink the task log and qemu console log to tmp/log/oeqa

This makes it easier for the AB scripts (particularly, collect-results)
to access and archive these items, as they can contain useful information
when ptests or other qemu tests fail (and also if they don't fail).

[YOCTO #14518]

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>