Make node use bounded amount of space on disk

[nazar-pc]

While with special finalization rules we ensure correct blocks are pruned, this is not everything that node stores.

One thing that node for sure stores is block headers, they are never pruned in Substrate by default: paritytech/polkadot-sdk#1570

I'm also suspecting state might also be retained while blocks are pruned, but I didn't investigate it, so might be wrong there.

Essentially we need to resolve upstream paritytech/polkadot-sdk#1570 and make use of it in Subspace.