Clean up and align the ByteBuffer order in test.

In normal case, the order will be configured as receiving the
ByteBuffer via NetlinkSocket.recvMessage() except unit test.
The order should be correctly set to algin with the behavior.
Incorrect order will cause incorrect content parsing.

Bug: 145328512
Test: atest NetworkStackTests NetworkStackNextTests
Change-Id: I496cc81315bea15a723a04be300ee39e2481b933