Ignore older UID state change callbacks in NPMS.

Since the onUidStateChanged() callbacks will be
happening from more than one thread, we need to make
sure we only handle the latest uid state change
callbacks and ignore any older callbacks that could
override the latest uid states in NPMS. In order to
this, every uid state change will be associated with
a unique seq number.

Also, remove the UidRecord.lastDispatchedProcStateSeq.
This was added as a safety measure to make sure we
don't unnecessarily end up waiting but it isn't
necessary and if we need to keep it, we need to add
a way to access it without holding global AMS lock,
which isn't worth the complexity.

Bug: 226299593
Test: atest tests/cts/hostside/src/com/android/cts/net/HostsideRestrictBackgroundNetworkTests.java
Change-Id: I631f5e01f6627916a96c930c22849a1d11eab636