netd_integration_test - add a test for bpf_skb_change_head at mtu limit

With an unfixed 4.14+ kernel this fails
(though see TODO this part is disabled atm):
  [66/68] NetdBpfTest#testBpfSkbChangeHeadAboveMTU: FAILED (1.202s)

  STACKTRACE:
  system/netd/tests/netd_test.cpp:284: Failure
  Expected equality of these values:
  pkt_size
  Which is: 1487
  -1
  system/netd/tests/netd_test.cpp:286: Failure
  Expected equality of these values:
  "detected missing kernel patch"
  Which is: 0x60c63650
  ""
  Which is: 0x60c729d1

Test: atest
Bug: 149816401
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I042430a8ce7a34031b052e83adc9b9938c3d8e5e