[ty] Avoid temporarily storing invalid multi-inference attempts (#22103)
## Summary
I missed this in https://github.com/astral-sh/ruff/pull/22062. This
avoids exponential runtime in the following snippet:
```py
class X1: ...
class X2: ...
class X3: ...
class X4: ...
class X5: ...
class X6: ...
...
def f(
x:
list[X1 | None]
| list[X2 | None]
| list[X3 | None]
| list[X4 | None]
| list[X5 | None]
| list[X6 | None]
...
):
...
def g[T](x: T) -> list[T]:
return [x]
def id[T](x: T) -> T:
return x
f(id(id(id(id(g(X64()))))))
```
Eventually I want to refactor our multi-inference infrastructure (which
is currently very brittle) to handle this implicitly, but this is a
temporary performance fix until that happens.
ruff
ad417282 - [ty] Avoid temporarily storing invalid multi-inference attempts (#22103)
