litep2p: Improve metric reasons for RequestResponse errors (#5077)

This PR improves the metrics reported by litep2p on request-response
errors.

Discovered while investigating:
- https://github.com/paritytech/polkadot-sdk/issues/4985


We are experiencing many requests that are `Refused` by litep2p in
comparison with libp2p.
The metric roughly approximates the sum of other reasons from libp2p.
This PR aims to provide more insights.

```
{__name__="substrate_sub_libp2p_requests_out_failure_total", chain="ksmcc3", instance="localhost:9615", job="substrate_node", protocol="/b0a8d493285c2df73290dfb7e61f870f17b41801197a149ca93654499ea3dafe/sync/2", reason="Remote has closed the substream before answering, thereby signaling that it considers the request as valid, but refused to answer it."}

    Last *: 3365
    Min: 3363
    Max: 3365
    Mean: 3365
    
    
{__name__="substrate_sub_libp2p_requests_out_failure_total", chain="ksmcc3", instance="localhost:9615", job="substrate_node", protocol="/b0a8d493285c2df73290dfb7e61f870f17b41801197a149ca93654499ea3dafe/beefy/justifications/1", reason="Remote has closed the substream before answering, thereby signaling that it considers the request as valid, but refused to answer it."}

    Last *: 3461
    Min: 3461
    Max: 3461
    Mean: 3461
```

Part of:
- https://github.com/paritytech/polkadot-sdk/issues/4681

cc @paritytech/networking

---------

Signed-off-by: Alexandru Vasile <[email protected]>