Update qos sai tests (sonic-net#14342)

1. update qos sai test for sn5400 according to the two PRs below

  a.  sonic-net#9583
  b.  sonic-net#12848

2. To stabilize testQosSaiQSharedWatermark[single_asic-wm_q_shared_lossy], update margin from 4 to 5 for spc4

Change-Id: Ic3919a9123cd968fb9d89013687cf31791684208

tests/qos/files/mellanox/special_qos_config.yml

@@ -33,5 +33,6 @@ qos_params:
             pkts_num_margin: 7
         wm_pg_shared_lossy:
             packet_size: 600
+            pkts_num_margin: 5
         wm_q_shared_lossy:
             packet_size: 600

tests/qos/qos_sai_base.py

@@ -352,7 +352,9 @@ def __getBufferProfile(self, request, dut_asic, os_version, table, port, priorit
 
         # Update profile static threshold value if  profile threshold is dynamic
         if "dynamic_th" in list(bufferProfile.keys()):
-            if dut_asic.sonichost.facts['platform'] == "x86_64-nvidia_sn5600-r0":
+            platform_support_nvidia_new_algorithm_cal_buffer_thr = ["x86_64-nvidia_sn5600-r0",
+                                                                    "x86_64-nvidia_sn5400-r0"]
+            if dut_asic.sonichost.facts['platform'] in platform_support_nvidia_new_algorithm_cal_buffer_thr:
                 self.__compute_buffer_threshold_for_nvidia_device(dut_asic, table, port, bufferProfile)
             else:
                 self.__computeBufferThreshold(dut_asic, bufferProfile)

tests/saitests/py3/sai_qos_tests.py

@@ -5113,7 +5113,7 @@ def runTest(self):
 
             if pkts_num_fill_min:
                 assert (q_wm_res[queue] == 0)
-            elif 'cisco-8000' in asic_type or "SN5600" in hwsku:
+            elif 'cisco-8000' in asic_type or "SN5600" in hwsku or "SN5400" in hwsku:
                 assert (q_wm_res[queue] <= (margin + 1) * cell_size)
             else:
                 if platform_asic and platform_asic == "broadcom-dnx":