Revert "enable pfcwd for backplane ports (#3759)"

[sdszhang]

This reverts commit 2866ccd.

After PFCWD is enabled on backplane in #3759, qos/test_qos_sai.py::TestQosSai::testQosSaiPfcXoffLimit[single_dut_multi_asic-xoff_1] and all non single-asic cases failed with the following error:

======================================================================
ERROR: sai_qos_tests.PFCtest
----------------------------------------------------------------------
Traceback (most recent call last):
  File "saitests/py3/sai_qos_tests.py", line 1789, in runTest
    pkt, int(self.test_params['pg']), asic_type, pkts_num_egr_mem)
  File "saitests/py3/sai_qos_tests.py", line 582, in fill_leakout_plus_one
    asic_type, int(pkts_num_egr_mem))
  File "saitests/py3/sai_qos_tests.py", line 626, in fill_egress_plus_one
    pkts_num_egr_mem + max_packets, pg_cntrs_base[queue], pg_cntrs[queue]))
RuntimeError: fill_egress_plus_one: Failure, sent 7884 packets, SQ occupancy bytes rose from 0 to 0

----------------------------------------------------------------------

as egress port is tx_disabled, PFC is generated from egress port back to backplane and triggered pfcwd on supervisor card. hence resulting in packet drop.

admin@sonic-sup-1:~$ show pfcwd stat -d all
            QUEUE       STATUS    STORM DETECTED/RESTORED     TX OK/DROP    RX OK/DROP    TX LAST OK/DROP    RX LAST OK/DROP
-----------------  -----------  -------------------------  -------------  ------------  -----------------  -----------------
 Ethernet-BP448:3  operational                      11/11  35404/1018833           0/0             0/8880                0/0
Ethernet-BP2240:3  operational                        2/2    3601/980808           0/0        3601/979813                0/0
Ethernet-BP2240:4  operational                        1/1          0/997           0/0              0/997                0/0
Ethernet-BP2244:3  operational                        2/2      7465/1990           0/0           2055/995                0/0
Ethernet-BP2244:4  operational                        1/1          1/994           0/0              1/994                0/0
Ethernet-BP4560:3  operational                        1/1        968/989           0/0            968/989                0/0
Ethernet-BP4560:4  operational                        1/1          1/983           0/0              1/983                0/0
Ethernet-BP4564:3  operational                        2/2        12/1974           0/0              7/988                0/0
Ethernet-BP4564:4  operational                        1/1          7/982           0/0              7/982                0/0
admin@sonic-sup-1:~$

What I did

Reverted back PR #3759

How I did it

Reverted back PR #3759

How to verify it

PFCtest passed after applying the patch manually. Full test_qos_sai is still running. will upload the result once it is done.

(Pdb) c
fill_egress_plus_one: Success, sent 6941 packets, SQ occupancy bytes rose from 0 to 1536
after send packets short of triggering PFC:
        recv_counters [0, 48251, 0, 0, 0, 1166406, 494656, 0, 0, 0, 21711040893, 1345, 48251, 0, 3019568, 1981, 0, 0]
        recv_counters_base [0, 48251, 0, 0, 0, 1166406, 494656, 0, 0, 0, 21700549309, 1344, 48251, 0, 3009234, 1980, 0, 0]
        xmit_counters [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 21763613747, 40252, 0, 0, 2352, 998, 0, 0]
        xmit_counters_base [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 21752352307, 40245, 0, 0, 2351, 998, 0, 0]

after send a few packets to trigger PFC:
        recv_counters [0, 48251, 0, 0, 0, 1238602, 494656, 0, 0, 0, 21717895805, 1345, 48251, 0, 3019609, 1981, 0, 0]
        recv_counters_base [0, 48251, 0, 0, 0, 1166406, 494656, 0, 0, 0, 21711040893, 1345, 48251, 0, 3019568, 1981, 0, 0]
        xmit_counters [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 21769594355, 40252, 0, 0, 2352, 999, 0, 0]
        xmit_counters_base [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 21752352307, 40245, 0, 0, 2351, 998, 0, 0]

after send packets short of ingress drop:
        recv_counters [0, 48251, 0, 0, 0, 1359193, 494656, 0, 0, 0, 21723777533, 1345, 48251, 0, 3019857, 1982, 0, 0]
        recv_counters_base [0, 48251, 0, 0, 0, 1238602, 494656, 0, 0, 0, 21717895805, 1345, 48251, 0, 3019609, 1981, 0, 0]
        xmit_counters [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 21776005939, 40252, 0, 0, 2353, 999, 0, 0]
        xmit_counters_base [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 21752352307, 40245, 0, 0, 2351, 998, 0, 0]

after send a few packets to trigger drop:
        recv_counters [0, 48272, 0, 0, 0, 1459846, 494656, 0, 0, 0, 21729769085, 1346, 48272, 0, 3019898, 1982, 0, 0]
        recv_counters_base [0, 48251, 0, 0, 0, 1359193, 494656, 0, 0, 0, 21723777533, 1345, 48251, 0, 3019857, 1982, 0, 0]
        xmit_counters [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 21781582707, 40252, 0, 0, 2354, 999, 0, 0]
        xmit_counters_base [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 21752352307, 40245, 0, 0, 2351, 998, 0, 0]

ok

----------------------------------------------------------------------
Ran 1 test in 65.702s

OK

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[sdszhang]

@abdosi @zhixzhu @alpeshspatel @rraghav-cisco @yejianquan for review

[yejianquan]

LGTM

[mssonicbld]

Cherry-pick PR to msft-202405: Azure/sonic-utilities.msft#122