qt, wallet: Drop unused parameter in WalletModel::setWalletEncrypted
Summary:
This is a backport of core-gui#109 [3/3]
https://github.com/bitcoin-core/gui/pull/109/commits/4146a31ccbb012ff552f303113979b48c086532b
Test Plan: ninja all check-all
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D10739