test: Add test for -blockversion

Summary:
-blockversion is currently untested, as in: The setting could be made a no-op without any tests failing. Fix that by adding an explicit test for it.

This is a backport of core#20167 [3/3]
https://github.com/bitcoin/bitcoin/pull/20167/commits/fa9b48549ca39b862a10bcfd90e3eac2a0e8ad2e

Note: we don't need the NORMAL_GBT_REQUEST_PARAMS helper, as Bitcoin ABC's normal getblocktemplate call needs no paramaters.

Test Plan: test/functional/test_runner.py mining_basic

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10679