Follow-up to #29625 and #30902

This PR reintroduces auto-intents for brackets in Python and fixes some
cases where an indentation would be triggered if it should not. For
example, upon typing

```python
a = []
```
and inserting a newline after, the next line would be indented although
it shoud not be.

Bracket auto-indentation was tested prior to #29625 but removed there
and the test updated accordingly. #30902 reintroduced this for all
brackets but `()`. I reintroduced this here, reverted the changes to the
test so that indents also happen after typing `()`. This is frequently
used for tuples and multiline statements in Python.

Release Notes:

- Improved auto-indentation when using round brackets in Python.