Mempool monitoring is dependent on single mempool

[f321x]

The mempool monitoring currently uses only one mempool. This could be insecure after restarting the coordinator backend node until it has collected a sufficiently sized mempool again. To make this less risky functionality to connect to multiple backends for mempool monitoring could be introduced to have some redundancy, especially in the case of large mempools (e.g. >300mb).

[khadar1020]

I will work on this issue