Add newlines before comments in E305 (#12606)
## Summary
There's still a problem here. Given:
```python
class Class():
pass
# comment
# another comment
a = 1
```
We only add one newline before `a = 1` on the first pass, because
`max_precedling_blank_lines` is 1... We then add the second newline on
the second pass, so it ends up in the right state, but the logic is
clearly wonky.
Closes https://github.com/astral-sh/ruff/issues/11508.
