gh-146615: Fix format specifiers in error messages for consistency and correctness

[sunmy2019]

There are 2 kinds of errors.

There are ~8 real mistakes.
Comply with C99 for va_list: https://en.cppreference.com/w/c/variadic/va_arg.html
Most of the changes are %d <-> %ld for int and Py_ssize_t.

• Issue: Some Unicode format specifiers are incorrect #146615

[picnixz]

I would suggest:

• 1 PR for errors in testcapi* etc.
• 1 PR for errors in Python/*
• 1 PR for errors in Objects/*
• 1 PR for errors in extension modules.

Or 1 PR for real mistakes, 1 PR for the rest.

[sunmy2019]

Split.

• 1 PR for errors in testcapi* etc.
  gh-146615: Fix format specifiers in test cextensions #146618

• 1 PR for errors in Python/*
  gh-146615: Fix format specifiers in Python/ directory #146619

• 1 PR for errors in Objects/*
  gh-146615: Fix format specifiers in Objects/ directory #146620

• 1 PR for errors in extension modules.
  gh-146615: Fix format specifiers in extension modules #146617