Revert "[dhcp_relay] Skip test_dhcpv6_relay for dualtor-aa (sonic-net…

…#12046)" (sonic-net#12309)

What is the motivation for this PR?
dhcpv6 relay failure in dualtor-aa was fixed by sonic-net#11695
Hence remove skip condition

How did you do it?
Remove skip test_dhcpv6_relay in dualtor-aa

How did you verify/test it?
Run test

tests/common/plugins/conditional_mark/tests_mark_conditions.yaml

@@ -306,20 +306,6 @@ dhcp_relay/test_dhcpv6_relay.py:
     conditions:
       - "platform in ['x86_64-8111_32eh_o-r0']"
 
-dhcp_relay/test_dhcpv6_relay.py::test_dhcp_relay_default:
-  skip:
-    reason: "Test is not supported in dualtor-aa"
-    conditions:
-      - https://github.com/sonic-net/sonic-mgmt/issues/12045
-      - "'dualtor-aa' in topo_name"
-
-dhcp_relay/test_dhcpv6_relay.py::test_dhcpv6_relay_counter:
-  skip:
-    reason: "Test is not supported in dualtor-aa"
-    conditions:
-      - https://github.com/sonic-net/sonic-mgmt/issues/12045
-      - "'dualtor-aa' in topo_name"
-
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