Currently it was not possible to run just the BlockToJsonVerboes benchmarsk because it did not set up everything it needed, running `bench_bitcoin -filter=BlockToJsonVerbose` caused this assert to fail:
```
bench_bitcoin: chainparams.cpp:506: const CChainParams& Params(): Assertion `globalChainParams' failed.
```
Initializing TestingSetup fixes this.
This is a backport of core#21170