[backport#12409] rpc: Reject deprecated reserveChangeKey in fundrawtransaction

Summary:
fa5f518 rpc: Reject deprecated reserveChangeKey in fundrawtransaction (MarcoFalke)

Apparently the meaty change in this backport was already done, except
for the test.

Backport of Core PR12409

Test Plan:

ninja all
test_runner.py rpc_fundrawtransaction

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D8212