Separate the timeout behavior from PacketRetransmittingState class.

The purpose is to make subclass that only requires timeout method
could extend from TimeoutState instead of PacketRetransmittingState,
avoiding the anti-pattern of using inheritance for code reuse only.

After refactoring, class inheritance relationship looks like:

LoggingState <-- TimeoutState <-- PacketRetransmittingState <-- DhcpInitState

Bug: 140223017
Test: atest NetworkStackTest
Change-Id: I585fa7942f7ddc8dc167a513c816f4534c120fc1
(cherry picked from commit eb61ab9aad76e896782c400015dbd2f1d9c62314)
CRs-fixed: 2583997