Allow to respond to piece cache changes during piece cache sync in cluster setup

[nazar-pc]

Right now piece cache sync can't be interrupted. This is fine for regular farmer, but in cluster setup where caches can appear and disappear at any time it causes problems because piece cache will try to store pieces at the piece cache that might be already offline and similarly it'll fail to discover new caches that might have been added in the meantime.

Originally reported on the forum: https://forum.autonomys.xyz/t/cluster-piece-cache-sync-timeout/4470?u=nazar-pc

Logs

cache.txt
controller.txt
nats.txt