bug: wakuPeerExchangeDiscovery doesn't seem to take pubsubTopics into account

[fbarbu15]

This is a bug report

Problem

When using wakuPeerExchangeDiscovery with a wrong(non-existent or empty) pubsubtopicArray the peerExchange still works and node are discovered. Peer Exchange does not take the passed pubsub topics into consideration.

Solution

Instead of saving all peers to the peer store, discard the peers that are not on the configured shard.

[chair28980]

@danisharora099 to inspect the issue and update with findings.

[danisharora099]

Right!
Pubsub topic is required to satiate BaseProtocol and is not taken into consideration while finding/saving peers, as peer exchange finds all peers and then Connection Manager ignores peers according to the pubsub topic.

We can not save peers in the peer store if they are not relevant to the configured pubsub topics

Updated the issue description to reflect the same