Update sync engine when adding ready condition

When adding a ready condition, we may need to unready
the sync-engine if it was ready so that it will wait.

Bug: 439102754
Test: TransitionTests#testDeferTransitionReady_deferStartedTransition
Flag: com.android.window.flags.migrate_basic_legacy_ready
Change-Id: I8546a50bd6965ef3bb2e64b93f786a2ac7b1f4b0