Remove a default value in distutils

Fixes #9799.

Stubtest started failing on our `setuptools` stubs because of a default value added to our stdlib `distutils` stubs. The reason for this is because our `setuptools` stubs erroneously claim here that the `setuptools._distutils.core.Distribution` class is the same as the stdlib `distutils.dist.Distribution` class:

https://github.com/python/typeshed/blob/06755e10ba0d39e7e4c18fcc2663d9da564a71ad/stubs/setuptools/setuptools/_distutils/core.pyi#L3

In actual fact, they're not, and they have different default values for this parameter. But reverting the addition of the default value is the simplest short-term fix for now.

(An alternative fix would be to just merge #9795.)

stdlib/distutils/dist.pyi

@@ -103,7 +103,7 @@ class Distribution:
     def get_command_packages(self): ...
     def get_command_class(self, command): ...
     def reinitialize_command(self, command, reinit_subcommands: int = 0): ...
-    def announce(self, msg, level=2) -> None: ...
+    def announce(self, msg, level: int = ...) -> None: ...
     def run_commands(self) -> None: ...
     def run_command(self, command) -> None: ...
     def has_pure_modules(self): ...