Merge #13967: [walletdb] don't report minversion wallet entry as unknown

Summary:
321159e53e800c1df2d8dfd6ac03374f1829c327 don't report minversion wallet entry as unknown (Gregory Sanders)

Pull request description:

It is known in WalletBatch::LoadWallet

Tree-SHA512: 82f7e12f48ae7d17317074ce5b5e27c70ba8334b04adbf7cc863f8169cc1aa460b9454571e2698aa00059c8c8f669fe19c0d40c4910dcded260ddca6ce78be9d

Backport of Core PR13967

Test Plan:

make check
test_runner.py wallet_*

Reviewers: O1 Bitcoin ABC, #bitcoin_abc, Fabien

Reviewed By: O1 Bitcoin ABC, #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D5111