[core] Fix NumericInput continuous change after unmount

Environment

• Package version(s): 5.x / current develop branch
• Operating System: Windows 11
• Browser name and version: Microsoft Edge 152

Code Sandbox

Link to a minimal repro (fork this code sandbox):

Steps to reproduce

1. Render a NumericInput with an onButtonClick callback.
2. Press and hold one of the increment/decrement buttons to start continuous changes.
3. Unmount the NumericInput while the button is still being held.
4. Wait for the continuous-change interval to continue firing.

Actual behavior

The continuous-change interval is not cleared when NumericInput is unmounted. As a result, onButtonClick can continue to be invoked after the component has been unmounted.

Expected behavior

Unmounting NumericInput should clean up the active continuous-change interval and mouseup event listener so that no further callbacks are triggered after unmount.

Possible solution

Clean up the continuous-change state during componentWillUnmount() by calling stopContinuousChange(), while preserving the existing AbstractPureComponent cleanup.