fullstack: increase test timeout
fullstack: increase test timeout

Database teardowns seem to have a lock contention issue.  This is a
workaround.

Change-Id: Ifd0957a86646c6a13a71b5bbf985f4694e37e943
Partial-bug: 1541742

cloudbase/neutron,sebrandon1/neutron,noironetworks/neutron,klmitch/neutron,sebrandon1/neutron,huntxu/neutron,cloudbase/neutron,wolverineav/neutron,MaximNevrov/neutron,MaximNevrov/neutron,eayunstack/neutron,eayunstack/neutron,igor-toga/local-snat,openstack/neutron,klmitch/neutron,noironetworks/neutron,openstack/neutron,mahak/neutron,mahak/neutron,igor-toga/local-snat,huntxu/neutron,bigswitch/neutron,wolverineav/neutron,mahak/neutron,openstack/neutron,bigswitch/neutron