Merge #12837: rpc: fix type mistmatch in listreceivedbyaddress

Summary:
05c03d1249 rpc: fix type mistmatch in listreceivedbyaddress (joemphilips)

Pull request description:

`txids` filed in return value is supposed be `string` but it was `numeric` in the help message

Tree-SHA512: 7d860994c2d1d9149b41fd7afefc1a44460eede5a023070fcc18b0a4a19a26c5eec5abd157038c15fe7d50a3390bdaf7a4823279129eb1458b0d3c6141a533ee

Backport of Core PR12837
https://github.com/bitcoin/bitcoin/pull/12837/

Test Plan:

make check
./bitcoind
./bitcoin-cli help listreceivedbyaddress

Reviewers: deadalnix, Fabien, jasonbcox, O1 Bitcoin ABC, #bitcoin_abc

Reviewed By: jasonbcox, O1 Bitcoin ABC, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D3887