meta/lib/oe/lsb.py: extract only the needed info from lsb-release

Instead of running lsb_release -a, a lsb_release -ir will be run.
This will prevent issue with distros that don't have all the needed
info in /etc/lsb-release file, in which case lsb_release won't generate
an error code.

Partial fix for [YOCTO #4071]

Signed-off-by: Cristian Iorga <cristian.iorga@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
qemuimage-testlib: Increase qemu startup timeouts

We are seeing timeouts on the autobuilder where qemu does start but the script
doesn't appear to be able to detect it in time. This patch increases the
timeouts since there seems little harm in doing so.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>