Comment 23 for bug 1799555

Found this problem again in [1].

In the test logs [2] we can see:
- 2019-10-15 09:23:10.682: the first DHCP agent is killed. We can see this in the last DHCP_1 log timestamps [3]
- 2019-10-15 09:24:30.437: the active wait to have the first network reschedule ends and the test starts tearing down the environment.

Meanwhile:
- 2019-10-15 09:24:32.363: the neutron server starts rescheduling the network to the second host [4].

Although increasing the waiting time in a test is never a good solution, in this case this is what we should do: increase the timeout of the active wait in TestDhcpAgentHA._wait_until_network_rescheduled. We saw in the related test case execution how the network rescheduling was done 80 seconds before the first DHCP agent was killed. We can raise the waiting time to 120 seconds (a very conservative value).

[1] https://2f600b8d6843c7d64afe-bbbb707b755a08f42bfac9929d4d55b4.ssl.cf2.rackcdn.com/688439/3/check/neutron-fullstack/119e702/testr_results.html.gz
[2] https://2f600b8d6843c7d64afe-bbbb707b755a08f42bfac9929d4d55b4.ssl.cf2.rackcdn.com/688439/3/check/neutron-fullstack/119e702/controller/logs/dsvm-fullstack-logs/TestDhcpAgentHA.test_reschedule_network_on_new_agent_Open-vSwitch-agent_.txt.gz
[3] https://2f600b8d6843c7d64afe-bbbb707b755a08f42bfac9929d4d55b4.ssl.cf2.rackcdn.com/688439/3/check/neutron-fullstack/119e702/controller/logs/dsvm-fullstack-logs/TestDhcpAgentHA.test_reschedule_network_on_new_agent_Open-vSwitch-agent_/neutron-dhcp-agent--2019-10-15--09-22-40-070799_log.txt.gz
[4] https://2f600b8d6843c7d64afe-bbbb707b755a08f42bfac9929d4d55b4.ssl.cf2.rackcdn.com/688439/3/check/neutron-fullstack/119e702/controller/logs/dsvm-fullstack-logs/TestDhcpAgentHA.test_reschedule_network_on_new_agent_Open-vSwitch-agent_/neutron-server--2019-10-15--09-22-31-039056_log.txt.gz