[backport#14653] Test coinbase category in wallet rpcs

Summary:
https://github.com/bitcoin/bitcoin/pull/14653/commits/f3f6dde56ead45072864123ed0a2bb04ec584b65

Depends on D7316

Concludes backport of Core PR14653

Test Plan:

ninja
./test/functional/test_runner.py wallet_coinbase_category

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D7317