net_test - extra debugging for ReadProcNetSocket() regexp match failures

See:
  https://android-build.googleplex.com/builds/submitted/5097760/kernel_test/latest/view/logs/build.log

ie.:
  ##### ./forwarding_test.py (5/23)
  E.
  ======================================================================
  ERROR: testForwardingCrashTcp (__main__.ForwardingTest)
  ----------------------------------------------------------------------
  Traceback (most recent call last):
    File "./forwarding_test.py", line 169, in testForwardingCrashTcp
      self.CheckForwardingByProto(IPPROTO_TCP)
    File "./forwarding_test.py", line 161, in CheckForwardingByProto
      self.CheckForwardingHandlerByProto(proto, netid, iface1, iface2)
    File "./forwarding_test.py", line 150, in CheckForwardingHandlerByProto
      self.CheckForwardingCrashTcp(netid, iif, oif)
    File "./forwarding_test.py", line 124, in CheckForwardingCrashTcp
      sockets = self.ReadProcNetSocket("tcp6")
    File "/host/usr/local/google/buildbot/src/partner-android/common-android-4.19/kernel/tests/net/test/net_test.py", line 462, in ReadProcNetSocket
      _, _, uid, _, _, refcnt, _, extra) = regexp.match(line).groups()
    AttributeError: 'NoneType' object has no attribute 'groups'

  ----------------------------------------------------------------------
  Ran 2 tests in 0.452s

  FAILED (errors=1)
  E.

  ...(and then it reruns and promptly fails again in the same way)...

  './forwarding_test.py' failed more than once, giving up

  #####

I've had no luck reproducing the failure locally...
But I'm guessing one of the 8 hex digit regexps is not matching due to printing
out a negative 64 bit integer (which requires 16 hex digits).

I'm intentionally leaving this in a way it can still fail, so we get to the
bottom of this and actually fix the regexps.

(while we're at it remove a spurious second | operator)

Bug: 118651133
Change-Id: I6fbdc563cedbba3648d74b6bea1911b94086d0f3