BUG: Series[int].loc setitem with Series[int] results in Series[float]
```
>>> pd.__version__
'1.3.0.dev0+1695.g55e58542db'
>>> 
>>> s = pd.Series([0, 0])
>>> s
0    0
1    0
dtype: int64
>>> 
>>> s2 = pd.Series([42])
>>> s2
0    42
dtype: int64
>>> 
>>> s.loc[0] = s2
>>> s
0    42.0
1     0.0
dtype: float64
>>> 
```

Does not need a release note, this issue is only on master as on 1.2.4 this raises `ValueError: No axis named 1 for object type Series` which was fixed in #39358

draft, since if we merge and backport #40555 first, we can also remove the patch in this PR.