SF: Set eTransactionFlushNeeded after queuing a transaction

Fixes a possible race where the transaction may not be queued
in the binder thread before the main thread wakes up to
flush the queues.

Bug: 251712581
Test: scroll on 90hz device and check all transactions are
applied

Change-Id: I1dbfb2368179d1a101e821e821d1374cd2842965