Chore: new json compilation mechanism

[akvlad]

What

Switch from fmt.Sprintf to json-iterator json creation method.

Why

CodeQL reported about a set of potentially vulnerable places in the code where json is compiled using fmt.Sprintf. The most concerning parts are already replaced. We have to refactor the rest.

How

1. Find all the functions where json is created using fmt.Sprintf and enumerate them.
2. Replace the fmt.Sprintf with json-iterator library as it is done here: https://github.com/metrico/qryn/blob/gigapipe/reader/service/queryRangeService.go#L226-L324
3. Make sure that all the tests are passed.