fix: Add limits to LiveQueryStore to prevent high memory usage

[dima74]

Description

Added two new config parameters which limits number of live queries (global and per-user). Default value for both is 128. This is needed to prevent high memory usage in cases when client sends a lot of queries with large output, but do not fully consume those queries (that is obtain only first batch and doesn't send requests for the next batches). Normally clients should not do this, but malicious third-party can send such requests to DDOS iroha peer. In case limits are exceeded, iroha peer will return error "429 too many requests" for the query request.

• Names of parameters:

[torii]
query_store_capacity = 128
query_store_capacity_per_user = 128

Also:

• Changed default value of query idle time from 30s to 10s (for the same reason to decrease potential peak memory usage)
• Changed default value of fetch size from 10 to 100 (I think it is strange that when query output has e.g. 1000 items, client currently has to send 100 requests to get full query result)

Some notes about implementation:

• Currently when adding new query, the message is send to mpsc::channel, and LiveQueryStore thread does the addition. I changed it to perform addition directly without mpsc::channel since we now need to check capacity and return error to client if it exceeds.

Linked issue

Closes #4830

Benefits

Add limit to number of live queries to prevent high memory usage in cases when client don't fully consume query output.

Checklist

• I've read CONTRIBUTING.md
• I've used the standard signed-off commit format (or will squash just before merging)
• All applicable CI checks pass (or I promised to make them pass later)
• (optional) I've written unit tests for the code changes
• I replied to all comments after code review, marking all implemented changes with thumbs up

[github-actions]

@BAStos525

[mversic]

@dima74 with_coverage is failing if you haven't noticed