feat(code): Limit the number of values in sync response to `cfg.sync.max_response_size`

[ancazamfir]

This is an issue remaining after #1070

The syncing node may request a value range for which the response exceeds the cfg.p2p.rpc_max_size.
cfg.p2p.rpc_max_size is sometimes used to overwrite cfg.sync.max_response_size.
The number of values per batch can be configured with sync_cfg.batch_size.

This issue is to address the following:

• Ensure that the response payload does not exceed:

  • the number of values required: i.e. if n values are requested do not respond with N>n values, AND
  • the min(cfg.p2p.rpc_max_size, cfg.p2p.rpc_max_size) in byte size

• Make sure that the syncing node does not penalize peers that respond with less than n values

See also these comments