alter ActiveP2pNetwork concept of close to in sync

[rolfyone]

• isInSync is often set when there's no other peers to sync to so its not a great measure

• moved the isCloseToInSync into recentChaindata

Documentation

• I thought about documentation and added the doc-change-required label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

[rolfyone]

i've done a few syncs on different networks, and its behaving as I expect, ready to review.

[tbenr]

There is a side effect with this, which can be replicated this way:

1. run a single interop node and let it progress the chain for a while
2. stop the node and wait until isCloseToInSync will return false
3. start the node again
4. the node SyncStateTracker service start will timeout and call onStartupTimeout
5. we are not in a state where the single node start building the chain again but never starts the gossip again (so it will never communicate with an eventual node joining the network later)

previous behaviour

new behaviour:

so if a new node connects you end up in this weird situation where we don't publish messages to the other peer even if it is connected and just synced to the head.

[tbenr]

I think we need ActiveEth2P2PNetwork to subscribe like network.subscribeConnect(peer -> onPeerConnected()); and make sure we start gossip when we are in sync and we got peers connected onPeerConnected

[tbenr]

@rolfyone pushed a commit to cover the condition i was mentioning.

[tbenr]

maybe we could provide isCloseToInSync on the onSyncStateChanged method, instead of isInSync. The consumer doesn't get much value by just receiving that event and most likely need to call recenChainData to get the info. Doing that we could avoid multiple calls (for each subscriber) to recentChainData (and also avoid subscriber to require recenChainData dep injection)