Revert "nvwave: Don't close the audio device..." (PR·#11024)
This reverts commit 633435db9d1abcf00bc47d047c3d3cd984b72109.
Instead of using a timer to close the audio device we will keep it open.
The initial requirement for keeping the device open no longer applies
see https://github.com/nvaccess/nvda/pull/11505#issuecomment-675146802
