Keep mentions of v3 in debug strings to help people who might not know
that TRUC is applied when version=3.
Also keep variable names in tests, as it is less verbose to keep v3 and v2.
Ensure we are checking sigop-adjusted virtual size by creating setups
and packages where sigop cost is larger than bip141 vsize.
Co-authored-by: Gregory Sanders <gsanders87@gmail.com>
