Camera3Device: Fix spurious onIdle callback during internal reconfig

Because the request thread went idle before it notified the parent to
reconfigure, the flag to avoid spurious notifications was set too
late; an idle notification would already be sent by then.

Move the flag setting to the beginning of the sequence to correctly
suppress all needed notifications.

Test: No crash in previously affected app; camera CTS continues to pass
Bug: 72392658
Change-Id: Id7d1f66bab455035bbec7b04f7dd4157ad94b773