Fix 'mempool min fee not met' debug output

Summary:

Output the value that is tested, rather than the unmodified fee value.

Backport of core PR12356 (main), PR12512 and PR12455 (fixes)
https://github.com/bitcoin/bitcoin/pull/12356/files
https://github.com/bitcoin/bitcoin/pull/12512/files
https://github.com/bitcoin/bitcoin/pull/12455/files

Test Plan:

make check
./test/functional/test_runner.py --extended

Reviewers: #bitcoin_abc, deadalnix, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Subscribers: jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D3503