Updated openstack/openstack
Project: openstack-infra/devstack-gate  709f2349c2e7e204bfe6f4ccec3e2113091adc61

don't delete grenade logs

we actually want to switch over to summary logs in the gate, so
we need to not delete the logs, as the console will be pretty
empty otherwise:

Change-Id: Ifae56479364ded13fb765ec6158f651888e828ea
bp:grenade-readability