Skip vxlan bfd tsa testcase4/5/6 due to issue#15728 (sonic-net#15978)

- What is the motivation for this PR?
Skip vxlan bfd tsa testcases 4/5/6 due to issue(sonic-net#15728)

- How did you do it?
Skip file on github issue

- How did you verify/test it?
Rerun the test and see it is skipped

Author: congh-nvidia

tests/common/plugins/conditional_mark/tests_mark_conditions.yaml

@@ -2374,6 +2374,7 @@ vxlan/test_vxlan_bfd_tsa.py::Test_VxLAN_BFD_TSA::test_tsa_case4:
     conditions:
       - "(is_multi_asic == True) or (platform not in ['x86_64-8102_64h_o-r0', 'x86_64-8101_32fh_o-r0', 'x86_64-mlnx_msn4600c-r0', 'x86_64-mlnx_msn2700-r0', 'x86_64-mlnx_msn2700a1-r0', 'x86_64-kvm_x86_64-r0', 'x86_64-mlnx_msn4700-r0', 'x86_64-nvidia_sn4280-r0'])"
       - "(asic_type in ['vs']) and https://github.com/sonic-net/sonic-buildimage/issues/19879"
+      - "https://github.com/sonic-net/sonic-mgmt/issues/15728"
 
 vxlan/test_vxlan_bfd_tsa.py::Test_VxLAN_BFD_TSA::test_tsa_case5:
   skip:
@@ -2382,6 +2383,7 @@ vxlan/test_vxlan_bfd_tsa.py::Test_VxLAN_BFD_TSA::test_tsa_case5:
     conditions:
       - "(is_multi_asic == True) or (platform not in ['x86_64-8102_64h_o-r0', 'x86_64-8101_32fh_o-r0', 'x86_64-mlnx_msn4600c-r0', 'x86_64-mlnx_msn2700-r0', 'x86_64-mlnx_msn2700a1-r0', 'x86_64-kvm_x86_64-r0', 'x86_64-mlnx_msn4700-r0', 'x86_64-nvidia_sn4280-r0'])"
       - "(asic_type in ['vs']) and https://github.com/sonic-net/sonic-buildimage/issues/19879"
+      - "https://github.com/sonic-net/sonic-mgmt/issues/15728"
 
 vxlan/test_vxlan_bfd_tsa.py::Test_VxLAN_BFD_TSA::test_tsa_case6:
   skip:
@@ -2390,6 +2392,7 @@ vxlan/test_vxlan_bfd_tsa.py::Test_VxLAN_BFD_TSA::test_tsa_case6:
     conditions:
       - "(is_multi_asic == True) or (platform not in ['x86_64-8102_64h_o-r0', 'x86_64-8101_32fh_o-r0', 'x86_64-mlnx_msn4600c-r0', 'x86_64-mlnx_msn2700-r0', 'x86_64-mlnx_msn2700a1-r0', 'x86_64-kvm_x86_64-r0', 'x86_64-mlnx_msn4700-r0', 'x86_64-nvidia_sn4280-r0'])"
       - "(asic_type in ['vs']) and https://github.com/sonic-net/sonic-buildimage/issues/19879"
+      - "https://github.com/sonic-net/sonic-mgmt/issues/15728"
 
 vxlan/test_vxlan_crm.py:
   skip: