Make dhcpmon counter test compatible with dual tor (sonic-net#11410)

What is the motivation for this PR?
Fix dhcpmon counter test failure on dualtor

How did you do it?
On single tor, REQUEST count is 3 because verify_dhcp_relay_pkt_with_no_padding sends two extra requests
Set dualtor REQUEST count to 1

How did you verify/test it?
Ran dhcp test suite

tests/dhcp_relay/test_dhcp_relay.py

@@ -334,11 +334,18 @@ def test_dhcp_relay_default(ptfhost, dut_dhcp_relay_data, validate_dut_routes_ex
                     marker_standby = loganalyzer_standby.init()
                     loganalyzer_standby.expect_regex = [expected_standby_agg_counter_message]
                 start_dhcp_monitor_debug_counter(duthost)
-                expected_agg_counter_message = (
-                    r".*dhcp_relay#dhcpmon\[[0-9]+\]: "
-                    r"\[\s*Agg-%s\s*-[\sA-Za-z0-9]+\s*rx/tx\] "
-                    r"Discover: +1/ +%d, Offer: +1/ +1, Request: +3/ +%d, ACK: +1/ +1+"
-                ) % (dhcp_relay['downlink_vlan_iface']['name'], dhcp_server_num, dhcp_server_num * 3)
+                if testing_mode == DUAL_TOR_MODE:
+                    expected_agg_counter_message = (
+                        r".*dhcp_relay#dhcpmon\[[0-9]+\]: "
+                        r"\[\s*Agg-%s\s*-[\sA-Za-z0-9]+\s*rx/tx\] "
+                        r"Discover: +1/ +%d, Offer: +1/ +1, Request: +1/ +%d, ACK: +1/ +1+"
+                    ) % (dhcp_relay['downlink_vlan_iface']['name'], dhcp_server_num, dhcp_server_num)
+                else:
+                    expected_agg_counter_message = (
+                        r".*dhcp_relay#dhcpmon\[[0-9]+\]: "
+                        r"\[\s*Agg-%s\s*-[\sA-Za-z0-9]+\s*rx/tx\] "
+                        r"Discover: +1/ +%d, Offer: +1/ +1, Request: +3/ +%d, ACK: +1/ +1+"
+                    ) % (dhcp_relay['downlink_vlan_iface']['name'], dhcp_server_num, dhcp_server_num * 3)
                 loganalyzer = LogAnalyzer(ansible_host=duthost, marker_prefix="dhcpmon counter")
                 marker = loganalyzer.init()
                 loganalyzer.expect_regex = [expected_agg_counter_message]