test: Add RegTestingSetup to setup_common

Summary:
This is a partial backport of Core PR17228 : https://github.com/bitcoin/bitcoin/pull/17228/commits/fa0a731d007a8e76d2740a2e6ead2289de77e475

Depends on D6356

Test Plan:

ninja all check

Reviewers: #bitcoin_abc, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D6358