test: Add test for -blockversion
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 [[https://github.com/bitcoin/bitcoin/pull/20167 | 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

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