Remove tx MIN_STANDARD_VERSION and MAX_STANDARD_VERSION

Summary:
The tx versions are now consensus, so we can use a single pair of constants and remove the duplicated code.
Note that the standardness check is kept as there is no reason to accept a transaction that violates the consensus rules.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D14029