chore: json-rpc and rest-api handlers are doubling the caches for messages.

[NagyZoltanPeter]

Background

Not pretty sure if it's by design and due to by decision. I found that currently relay rest-api and json-rpc maintain different message caches and doubles to handlers to be called to cache the messages.
It is the same currently for legacy filter as well.
I think it is waste of resources and can be refactored for an optimal solution.

Details

When installing handlers on App side we are providing different cache instances for rest and rpc handlers.
Also current design does not support using same cache.

[chair28980]

Closing per discussion at nwaku pm 2024-01-02.

Issue no longer relevant after removal of json-rpc.