Shreds are always zero-padded

[sakridge]

Problem

Shreds are always zero padded to 1320 bytes even if the payload is less than that. This is most likely a cause of 3x bandwidth and storage requirements than necessary on an idle network.

Proposed Solution

Only transmit and store the used part of the shred.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[sakridge]

Fixed by #16602