Wrong `unreachable` note in `finally` section

[tyralla]

@A5rocks found the following bug when discussing #19118:

def f4() -> None:
 while int():
 try:
 x = 1
 if int():
 x = ""
 break
 if int():
 while int():
 if int():
 x = None
 break
 finally:
 if isinstance(x, str):
 print("hello :)") # E: Statement is unreachable
 reveal_type(x) # N: Revealed type is "Union[builtins.int, builtins.str, None]

This bug does not need a loop and hence can be simplified to:

# Mypy 1.16.0
# --allow-redefinition-new --local-partial-types --warn-unreachable

def f() -> None:
 try:
 x = 1
 if int():
 x = ""
 return
 if int():
 x = None
 return
 finally:
 reveal_type(x) # N: Revealed type is "Union[builtins.int, builtins.str, None]" \
 # N: Revealed type is "builtins.int"
 if isinstance(x, str): # E: Subclass of "int" and "str" cannot exist: would have incompatible method signatures
 reveal_type(x) # E: Statement is unreachable \
 # E: Revealed type is "builtins.str"
 reveal_type(x) # N: Revealed type is "Union[builtins.int, builtins.str, None]" \
 # N: Revealed type is "builtins.int"

A first idea on how to fix this.