[backport#13082] Tests: don't test against min relay fee information in mining_prioritisetransaction.py

Summary:
1accfbc Output values for "min relay fee not met" error (Kristaps Kaupe)

• https://github.com/bitcoin/bitcoin/pull/13032/commits/1accfbcf465db19a9482d2ba129a66ded316f46e

bd9d67b752 Don't test against min relay fee information in mining_prioritisetransaction.py (Kristaps Kaupe)

• https://github.com/bitcoin/bitcoin/pull/13082/commits/bd9d67b752c64e6e858c32b953dd28fd5e36d832

Note: Changes to mining_prioritisetransaction.py made in 13032 are undone in 13082.

Backport of Core PR13082 and PR13032

Test Plan:

ninja all
test_runner.py mining_prioritisetransaction.py

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D8542