[network] Confirm and get rid of keep-alives in Notifications protocol

[dmitry-markin]

After #6248 is merged, manually keeping streams alive during additional keep-alive timeout should not be needed.

Confirm this and get rid of it.

[nazar-pc]

I believe this is what #6109 does, I specifically did kademlia_legacy_protocol: _, in #6248 to reduce inevitable merge conflict with it.

[dmitry-markin]

I believe this is what #6109 does, I specifically did kademlia_legacy_protocol: _, in #6248 to reduce inevitable merge conflict with it.

This seems not related to Notifications protocol keep-alive timeouts for me.

[nazar-pc]

Indeed, I didn't read it carefully 🤦‍♂️

[lexnv]

Indeed, believe we can remove it. Lets do it as a follow-up to not alter the started tests.

It looks like with this approach we are keeping the connection alive for at least 5 seconds of inactivity:

polkadot-sdk/substrate/client/network/src/protocol/notifications/handler.rs

Line 107 in 7903b11

const INITIAL_KEEPALIVE_TIME: Duration = Duration::from_secs(5);