Add ip/radv test to pr test yml and mclag/nat/sflow test to skip yml (#…

…13836)

What is the motivation for this PR?
Elastictest performs well in distribute running PR test in multiple KVMs, which support us to add more test scripts to PR checker.

How did you do it?
Add ip/radv test to pr test yml and mclag/nat/sflow test to skip yml

How did you verify/test it?
Test on KVM

.azure-pipelines/pr_test_scripts.yaml

@@ -241,6 +241,7 @@ t1-lag:
   - http/test_http_copy.py
   - iface_namingmode/test_iface_namingmode.py
   - ip/test_ip_packet.py
+  - ip/test_mgmt_ipv6_only.py
   - ipfwd/test_dip_sip.py
   - ipfwd/test_mtu.py
   - lldp/test_lldp.py
@@ -252,6 +253,7 @@ t1-lag:
   - platform_tests/test_cpu_memory_usage.py
   - process_monitoring/test_critical_process_monitoring.py
   - qos/test_buffer.py
+  - radv/test_radv_restart.py
   - route/test_default_route.py
   - route/test_route_consistency.py
   - route/test_route_flap.py

.azure-pipelines/pr_test_skip_scripts.yaml

@@ -7,6 +7,11 @@ t0:
   - k8s/test_config_reload.py
   - k8s/test_disable_flag.py
   - k8s/test_join_available_master.py
+  # Mclag test only support on t0-mclag platform which is not in PR test
+  - mclag/test_mclag_l3.py
+  # Nat feature is default disabled on both KVM and physical platforms
+  - nat/test_dynamic_nat.py
+  - nat/test_static_nat.py
   # Neighbor type must be sonic
   - ospf/test_ospf.py
   - ospf/test_ospf_bfd.py
@@ -43,6 +48,8 @@ t0:
   - restapi/test_restapi.py
   # Route flow counter is not supported on vs platform
   - route/test_route_flow_counter.py
+  # Sflow feature is default disabled on vs platform
+  - sflow/test_sflow.py
   - snmp/test_snmp_phy_entity.py
   # Remove from PR test in https://github.com/sonic-net/sonic-mgmt/pull/6073
   - cacl/test_ebtables_application.py