`partial` plugin does not handle overloads

Bug Report

it appears the new partial plugin added in mypy 1.11 doesn't properly handle overloads (and just picks the first one)

To Reproduce

import functools
from typing import assert_type, overload

@overload
def identity(x: int, *, p: str) -> int: ...
@overload
def identity(x: str, *, p: str) -> str: ...
def identity(x: int | str, *, p: str) -> int | str: return x


p = functools.partial(identity, p='hi')
assert_type(p(1), int)
assert_type(p('hi'), str)

Expected Behavior

(no errors)

Actual Behavior

$ mypy t.py 
t.py:13: error: Expression is of type "int", not "str"  [assert-type]
Found 1 error in 1 file (checked 1 source file)

Your Environment

• Mypy version used: 1.11.0
• Mypy command-line flags: none
• Mypy configuration options from mypy.ini (and other config files): none
• Python version used: 3.12.2

Reproduce the issue with the provided functools.partial, overload, and assert_type example by running mypy t.py. Trace the partial plugin's handling of overloaded callables and add coverage for both int and str arguments. Done means the example reports no errors and preserves both inferred return types.