a9910d82c3 contrib: Adjust output to current test format (Akio Nakamura)
Pull request description:
This PR makes the output of ```gen_base58_test_vectors.py``` to fit to current test format.
The test has already been changed(separated) from ```base58_test``` to ```key_io_test```, so change the file name of this script as well.
(This will solve #13553 )
Tree-SHA512: 2986009acd734edd5b6ee0a5efed9e8d156c99b1919a0e9f6ffdd4c863f52f4d1c6bfdaca359937ea380e311dda559d96449fc6a7224092c1fb2517ee5b83369
# Conflicts:
# contrib/testgen/gen_base58_test_vectors.py
