Remove babel stubs

[sobolevn]

It is now time!
Closes #9829

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

apprise (https://github.com/caronc/apprise)
+ setup.py:42: error: Library stubs not installed for "babel.messages"  [import]
+ setup.py:42: note: Hint: "python3 -m pip install types-babel"
+ setup.py:42: note: (or run "mypy --install-types" to install all missing stub packages)

sphinx (https://github.com/sphinx-doc/sphinx)
- sphinx/util/i18n.py: note: In function "format_date":
- sphinx/util/i18n.py:214:28: error: Incompatible types in assignment (expression has type "Callable[[Union[time, datetime, float, None], Union[Literal['full', 'long', 'medium', 'short'], str], Optional[tzinfo], Union[Locale, str, None]], str]", variable has type "Callable[[Optional[date], Union[Literal['full', 'long', 'medium', 'short'], str], Union[Locale, str, None]], str]")  [assignment]
- sphinx/util/i18n.py:216:28: error: Incompatible types in assignment (expression has type "Callable[[Union[date, time, float, None], Union[Literal['full', 'long', 'medium', 'short'], str], Optional[tzinfo], Union[Locale, str, None]], str]", variable has type "Callable[[Optional[date], Union[Literal['full', 'long', 'medium', 'short'], str], Union[Locale, str, None]], str]")  [assignment]