[backport#15087] Error if rpcpassword contains hash in conf sections

Summary:
8cff83124bcac936ecc6add6dca72b125a79a08f Error if rpcpassword contains hash in conf sections (MeshCollider)

Pull request description:

Fixes #15075

Tree-SHA512: 08ba2a2e9a7ea228fc0e0ff9aa76da1fecbe079e3b388304a28b6399e338a4b3a38b03ab03aca880e75f14a8d2ba75ceb31a385d7989cd66db5193a79f32c4e5

Depends on D5756

This is a backport of Core PR15087

Test Plan:

ninja
test_runner.py feature_config_args.py

Reviewers: deadalnix, #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D5757