test: Add test that addmultisigaddress fails for watchonly addresses
test: Add test that addmultisigaddress fails for watchonly addresses

Github-Pull: #15831
Rebased-From: fab6a0a659bb856e4598af3e0679fc37d5239478

chaincoin/chaincoin,chaincoin/chaincoin,chaincoin/chaincoin,chaincoin/chaincoin,chaincoin/chaincoin,chaincoin/chaincoin