Remove excess debounce + bind calls

[evansolomon]

The function being called (doSearch) is already debounced and in the correct this context. Calling _.debounce(someFunction, timeout)(args) is essentially the same thing as setTimeout(function () {someFunction(args)}, timeout), which doesn't really make sense here.

Since doSearch is already debounced there's no reason for delaying the call to it, and which point there's no reason for binding to the current context, at which point it can just be a plain old boring function call.

[afercia]

Please see related #26600, should be considered for commit together.

[azaozz]

In 31995:

Themes screen: remove extra debounce when searching.
Props evansolomon. Fixes #31812.