VtsHalAudioEffectTargetTest: Fix crash issue

Ensure all pending binder transactions are completed before proceeding. Add a delay to allow the binder destruction to propagate and ensure the remote objects are properly cleaned up.

Bug: 272442019
Test: atest VtsHalAudioEffectV7_0TargetTest

Change-Id: I6dc054b8f7895334c31c5579afb86eacba28d832