c409b1adac [rpc] Reduce scope of cs_main and cs_wallet locks in listtransactions (João Barbosa)
Pull request description:
Trivial change, no behaviour change.
Benchmark done as follow:
- run with `-regtest`
- wallet with 5000 transactions
- measured the time spent with the lock and the total time
- times are an average of 100 `listtransactions --count=...` calls
| `--count` | lock (ms) | total (ms) | saving |
|--:|--:|--:|--:|
| 10 | 0.2230 | 0.2510 | 11% |
| 100 | 2.5150 | 2.8690 | 12% |
| 1000 | 20.0320 | 23.3490 | 14% |
| 10000 | 105.2070 | 125.5310 | 16% |
Tree-SHA512: ebedfeeb4c8ad75c89128e53cae976a82967dbb5ffd129da0f7204ccf9c3c15070b3d509f3767bebd745512e410200cc546147c836e82409f95fc9b8d14fc3ed
Backport of Core [[https://github.com/bitcoin/bitcoin/pull/12330 | PR12330
Reviewer note: the change might be easier to see with `w=1`.