Fix: smth wrong with database & related queries

[Errorist79]

For ex), there is an abnormal latency in queries like {chain}/blocks where we fetch data from the database.
The same is the case with the {chain}/evm/polls and /validator/heartbeats/{operator_address} endpoints.
Also, it could be something like a memory leak etc, mongodb is consuming more resources than expected.

• investigate why queries are lagging so much and push a fix.
• investigate mongodb's resource consumption.