[test_dhcp] Drop extra quotes

This test is failing for TF with
'test.domain' not in 'search bad\nnameserver 10.100.0.2\n'

Dropping extra quotes around domain name resolves issue.
Tested with OVS setup test is passing as well.

Related-PROD: PRODX-26370
Change-Id: I2583a1cf24ac19b60f8ef771ee9a4e5bf271ae3e
diff --git a/neutron_tempest_plugin/scenario/test_dhcp.py b/neutron_tempest_plugin/scenario/test_dhcp.py
index d0545e2..31d2930 100644
--- a/neutron_tempest_plugin/scenario/test_dhcp.py
+++ b/neutron_tempest_plugin/scenario/test_dhcp.py
@@ -66,7 +66,7 @@
         test_domain = "test.domain"
         extra_dhcp_opts = [
             {'opt_name': 'domain-name',
-             'opt_value': '"%s"' % test_domain}]
+             'opt_value': '%s' % test_domain}]
         port = self.create_port(
             network=self.network, name=self.rand_name,
             security_groups=[self.security_group['id']],