* Convert debouncer async_shutdown to be a normal function
nothing was being awaited here and the shutdown call was only used
in integrations marked internal and other internals. Its possible
that a custom component might have been using the method but it
seemed uncommon enough that it did not warrent marking as a breaking
change. The update coordinator is no longer awaiting anything in
async_shutdown either now but it seemed likely that this use
would get subclassed.
* fix