[sovereign] Filter out topics/shard ids to broadcast

[mariusmihaic]

Reasoning behind the pull request

• Whenever having ougoing operations with shardID = MainChainShardID, broadcast of data will try to write on a "cross shard" topic with main chain, which is invalid and cause warns.

Proposed changes

• Filter out/skip broadcasting p2p data to main chain

Testing procedure

Pre-requisites

Based on the Contributing Guidelines the PR author and the reviewers must check the following requirements are met:

• was the PR targeted to the correct branch?
• if this is a larger feature that probably needs more than one PR, is there a feat branch created?
• if this is a feat branch merging, do all satellite projects have a proper tag inside go.mod?