tests: Run run-tests.py as root from run-all.sh

tests: Run run-tests.py as root from run-all.sh

This will be needed to be able to control dynamic mac80211_hwsim
operations like adding and removing a phy. In the past, it has been
possible to start the main programs as root and then use non-root
account for run-tests.py. However, there is already a large number of
cases within the test scripts where sudo is needed. Moving that
requirement to execution of run-tests.py allows those to be simplified
as well.

Signed-off-by: Jouni Malinen <j@w1.fi>