Drop strict-order flag from dnsmasq invocation

Without this flag, dnsmasq prefers to ask the servers that
are known to be up, rather than hitting servers that are either
down or known to be broken. This greatly reduces responsivity
impact of broken upstream servers.

Closes-Bug: #1746000
Change-Id: Ieee4dafc578c3bda0935fcdb80faad6c342a10e9

neutron/agent/linux/dhcp.py

@@ -328,7 +328,6 @@ class Dnsmasq(DhcpLocalProcess):
             'dnsmasq',
             '--no-hosts',
             _no_resolv,
-            '--strict-order',
             '--except-interface=lo',
             '--pid-file=%s' % pid_file,
             '--dhcp-hostsfile=%s' % self.get_conf_file_name('host'),

neutron/tests/unit/agent/linux/test_dhcp.py

@@ -1195,7 +1195,6 @@ class TestDnsmasq(TestBase):
             'dnsmasq',
             '--no-hosts',
             no_resolv,
-            '--strict-order',
             '--except-interface=lo',
             '--pid-file=%s' % expected_pid_file,
             '--dhcp-hostsfile=/dhcp/%s/host' % network.id,