[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
1 file changed