`@deprecated` doesn't work with non-overloaded constructors

Bug Report, To Reproduce, & Actual Behaviour

This is similar to #19588, but that was fixed on master for the case when __init__ is overloaded.

In the non-overloaded case, @deprecated still doesn't report anything (mypy Playground):

To Reproduce

from typing import overload
from typing_extensions import deprecated, Self

class Some:
    @deprecated("reason")
    def __new__(cls, x: str) -> Self: ...

Some('test')  # No reports here

class Some2:
    @deprecated("reason")
    def __init__(self, x: str) -> None: ...

Some2('test')  # No reports here

Expected Behavior

Some('test')  # E: function Some.__new__ is deprecated: reason  [deprecated]
Some2('test')  # E: function Some.__init__ is deprecated: reason  [deprecated]

Your Environment

• Mypy version used: 1.18.2, master

Start by reproducing the non-overloaded Some.new and Some2.init cases in the linked mypy Playground, then compare their handling with the overloaded case from #19588. Done means both constructor calls emit the expected [deprecated] diagnostics shown in the issue.