remove qtaguid parsing

This removes the legacy (and untested) xt_qtaguid
non-ebpf code path (ie. dead code).

Test: git grep 'QTAGUID_IFACE_STATS|QTAGUID_UID_STATS|parseIfaceStats|parseUidStats'
  finds nothing
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I922910238474f2cfb74eba19b219bc792ce4abc3