Fix dictionary editor steals focus when reloading script

[Dowsley]

Fix https://github.com/godotengine/godot/issues/96913

The default value on the form of a typed dictionary (e.g. 0 for an int) would count as an "unsaved change", thus triggering a update_property call, and would trigger the focus.

I am not aware of any case in which focus trigger to the "New Key" or "New Pair" inspectors is desired. Assuming this correct, the proposed change is the simplest possible fix I could find.