false positive on map with a conditional expression

Nobody has claimed this yet.

**Describe the bug**
a map with a conditional expression where both branches result in `str` is deduced to be of type `map[str | _T1@__new__]` instead of `map[str]`

**Code or Screenshots**

```python
from typing import Iterable

def print_branch_versions(branches: Iterable[str], branch_versions: Iterable[str]):
for [branch, version] in zip(branches, branch_versions):
print(f'{branch}: {version}')

branches: list[str] = []
branch_versions = map(lambda branch: (
f'{branch}-1.0'
if branch.startswith("versioned")
else branch
), branches)
print_branch_versions(branches=branches, branch_versions=branch_versions)
```

Pyright's output:
```
Argument of type "map[str | _T1@__new__]" cannot be assigned to parameter "branch_versions" of type "Iterable[str]" in function "print_branch_versions"
"map[str | _T1@__new__]" is incompatible with protocol "Iterable[str]"
"__iter__" is an incompatible type
Type "() -> map[str | _T1@__new__]" is not assignable to type "() -> Iterator[_T_co@Iterable]"
Function return type "map[str | _T1@__new__]" is incompatible with type "Iterator[_T_co@Iterable]"
"map[str | _T1@__new__]" is incompatible with protocol "Iterator[_T_co@Iterable]" (reportArgumentType)
```

Code sample in [pyright playground](https://pyright-play.net/?code=GYJw9gtgBALgngBwJYDsDmUkQWEMoCSMApiAIYBGANsQFC0AmxwUCIqMA%2BheSgMYALTgDdSAZyRgUYgBQ8y-AcTEAuQiXLViAbTEwQAXQA0UeYpHjJ0tUVKUau-QYCUK2lA9RguKNrOCTURAJKQNMFCgALyQEOV5BZRN-ISCQ6Vd3Tyy2DhlgAHIAb2SAXzVC1KsS-Od6ZOU1KiQ9R0MoAF5fA1pki2CrMQ6oCDJYqjIICgYyU3iBNRlMjwLiuZKAWgBGADoABnylzBZk7b0yPDEAdyQYARkAIkqpYgZ72qziKjFiWYVBWmcSTmylqORQXF6T2kcT%2BSjE7XqYiBsL6aXhkMsUjEtSAA)

Mypy is happy with this code: https://mypy-play.net/?mypy=latest&python=3.12&gist=86baf62660db59c5c4af554a531ffed5

Explicitly casting the else branch to `str` resolves the error.

Verify the diagnostic in the linked Pyright playground, then trace inference for the lambda's conditional expression and map construction. Done when the example no longer reports an argument-type error and the inferred result is compatible with Iterable[str].

Written by the indexing model from the issue text.