Changing method's name with autocompletion creates extra parentheses

[KoBeWi]

Simple example, you have this code:

You decide you want to use physics_process():

This happens:

Autocompletion shouldn't put anything after method name if it already contains opening parenthesis. Stuff like this happens too:

(when renaming func1 call to another one)

[akien-mga]

Related to #16223.

[KoBeWi]

Still valid in bcf7e51