Fix use-maxsplit-arg warnings

Noticed a few test files had these warnings, fixed them.
No functional change.

TrivialFix

Change-Id: I082baf04588e3f96a975c8fb2d74b5ec1b987801

neutron/tests/unit/agent/dhcp/test_agent.py

@@ -2282,7 +2282,7 @@ class TestDeviceManager(base.BaseTestCase):
         expected = ('dhcp1ae5f96c-c527-5079-82ea-371a01645457-12345678-1234-'
                     '5678-1234567890ab')
         # the DHCP port name only contains the hostname and not the domain name
-        local_hostname = cfg.CONF.host.split('.')[0]
+        local_hostname = cfg.CONF.host.split('.', maxsplit=1)[0]
 
         with mock.patch('uuid.uuid5') as uuid5:
             uuid5.return_value = '1ae5f96c-c527-5079-82ea-371a01645457'

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

@@ -1468,12 +1468,14 @@ class TestDnsmasq(TestBase):
                     s.ipv6_address_mode == constants.DHCPV6_STATEFUL):
                 if s.ip_version == constants.IP_VERSION_4:
                     expected.extend([prefix % (
-                        s.id, s.cidr.split('/')[0],
+                        s.id, s.cidr.split('/', maxsplit=1)[0],
                         netaddr.IPNetwork(s.cidr).netmask, lease_duration,
                         seconds)])
                 else:
                     expected.extend([prefix6 % (
-                        s.id, s.cidr.split('/')[0], s.cidr.split('/')[1],
+                        s.id,
+                        s.cidr.split('/', maxsplit=1)[0],
+                        s.cidr.split('/', maxsplit=1)[1],
                         lease_duration, seconds)])
                 possible_leases += netaddr.IPNetwork(s.cidr).size
 

neutron/tests/unit/extensions/test_flavors.py

@@ -461,7 +461,8 @@ class FlavorPluginTestCase(test_db_base_plugin_v2.NeutronDbPluginV2TestCase,
         self.service_providers.return_value = providers
         for provider in providers:
             self.service_manager.add_provider_configuration(
-                provider.split(':')[0], provconf.ProviderConfiguration())
+                provider.split(':', maxsplit=1)[0],
+                provconf.ProviderConfiguration())
 
         db_api.CONTEXT_WRITER.get_engine()
 

neutron/tests/unit/extensions/test_servicetype.py

@@ -244,7 +244,7 @@ class ServiceTypeManagerExtTestCase(ServiceTypeExtensionTestCaseBase):
         st_db.ServiceTypeManager._instance = None
         self.manager = st_db.ServiceTypeManager.get_instance()
         for provider in service_providers:
-            service_type = provider.split(':')[0]
+            service_type = provider.split(':', maxsplit=1)[0]
             self.manager.add_provider_configuration(
                 service_type, provconf.ProviderConfiguration(
                     svc_type=service_type))