…onic-net#12084)

What is the motivation for this PR?
Regarding to 7050qx's QoS SAI test for topo t0:

test port select result is as below:
testPortIds={0: {0:
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]}};

and 1,2,3 are low speed breakout port. as below:

admin@bjw-can-7050qx-3:~$ show int st
Interface Lanes Speed MTU FEC Alias Vlan Oper Admin Type Asym PFC

 Ethernet0                9      10G   9100    N/A     Ethernet1          routed      up     down                            SFP/SFP+/SFP28         off
 Ethernet1               10      10G   9100    N/A     Ethernet2           trunk      up       up                            SFP/SFP+/SFP28         off
 Ethernet2               11      10G   9100    N/A     Ethernet3           trunk      up       up                            SFP/SFP+/SFP28         off
 Ethernet3               12       1G   9100    N/A     Ethernet4           trunk      up       up                            SFP/SFP+/SFP28         off
 Ethernet4      13,14,15,16      40G   9100    N/A   Ethernet6/1           trunk      up       up  QSFP+ or later with SFF-8636 or SFF-8436         off
it cause two issue:

caused using wrong test target porfile for qos sai test. as below:

  profileName = ingressLosslessProfile["profileName"]      >>>>> [Xu]: just get profile of first test port, in this function.
  logger.info(
      "Lossless Buffer profile selected is {}".format(profileName))

  if self.isBufferInApplDb(dut_asic):
      profile_pattern = "^BUFFER_PROFILE_TABLE\\:pg_lossless_(.*)_profile$"
  else:
      profile_pattern = "^BUFFER_PROFILE\\|pg_lossless_(.*)_profile"
  m = re.search(profile_pattern, profileName)
  pytest_assert(m.group(1), "Cannot find port speed/cable length")

  # portSpeedCableLength = m.group(1)
  portSpeedCableLength = "40000_300m"     >>>> [Xu]: according to above sample result of test port selection, first port' id is 1 (it's Etherent1), the corresponding PG lossless porfile is "pg_lossless_10000_300m_profile". so we can never get expected pg_lossless_40000_300m_profile profile.
cause qos sai test traffic go through low speed breakout port rather than high speed 40G port
and eventually, caused Xon case failure.

How did you do it?
remove low speed port out of test port list

How did you verify/test it?
pass UT