Changed get value to use get() function in test

Getting value by indexing could cause KeyError if value
does not exist, instead call get() function which will return
None if value does not exist.

Also moved add_log_marker() function earlier to not accidently miss
the syslog.

tests/test_buffer_traditional.py

@@ -277,15 +277,16 @@ def test_no_pg_profile_for_speed_and_length(self, dvs: DockerVirtualSwitch, setu
 
             # Save original cable length
             fvs_cable_len = self.config_db.get_entry("CABLE_LENGTH", "AZURE")
-            orig_cable_len = fvs_cable_len[self.INTF] if fvs_cable_len else None
+            orig_cable_len = fvs_cable_len.get(self.INTF) if fvs_cable_len else None
 
             # Save original port speed and admin status
             fvs_port = self.config_db.get_entry("PORT", self.INTF)
-            orig_port_speed, orig_port_status = (fvs_port["speed"], fvs_port["admin_status"]) if fvs_port else (None, None)
+            orig_port_speed = fvs_port.get("speed") if fvs_port else None
+            orig_port_status = fvs_port.get("admin_status") if fvs_port else None
 
             # Save original port qos map
             fvs_qos_map = self.config_db.get_entry("PORT_QOS_MAP", self.INTF)
-            orig_cable_len = fvs_qos_map["pfc_enable"] if fvs_qos_map else None
+            orig_cable_len = fvs_qos_map.get("pfc_enable") if fvs_qos_map else None
 
             ######################################
             ## Send configurations to CONFIG_DB ##
@@ -300,6 +301,10 @@ def test_no_pg_profile_for_speed_and_length(self, dvs: DockerVirtualSwitch, setu
             # Configure PFC enable
             self.set_port_qos_table(self.INTF, test_port_pfc_enable)
 
+            # Add marker to log to make syslog verification easier
+            # Set before setting admin status to not miss syslog
+            marker = dvs.add_log_marker()
+
             # Configure admin status
             dvs.port_admin_set(self.INTF, test_port_status)
 
@@ -310,8 +315,6 @@ def test_no_pg_profile_for_speed_and_length(self, dvs: DockerVirtualSwitch, setu
             ## Verification ##
             ##################
 
-            # Add marker to log to make syslog verification easier
-            marker = dvs.add_log_marker()
 
             # Check syslog if this error is present. This is expected.
             self.check_syslog(marker, "Failed to process invalid entry, drop it")