[network/p2p] Redesign Push Gossip

[patrick-ogrady]

Related: ava-labs/coreth#497

Why this should be merged

A network incident was caused by network amplification due to re-push gossip. This removes push gossip for transactions learned about over the p2p network.

How this works

• Initially pushing a transaction to the network is now expected to be done solely by the node issuing the transaction.
• Nodes will still perform pull gossip to fully spread the transaction throughout the network.
• For simplicity, this change also removes the legacy push gossip mechanisms from all primary network chains.
• All critical parameters to this algorithm can be parameterized by the node issuing transactions. The default gossip values are intentionally set fairly conservatively, and can be modified if E2E TTF of transactions is longer than expected.

The added parameters to the P-chain and X-chain network configs are:

• push-gossip-discarded-cache-size
• push-gossip-max-regossip-frequency
• push-gossip-frequency

The added parameters to the C-chain config are:

• push-gossip-frequency
• pull-gossip-frequency

How this was tested

• Additional unit tests
• CI

[StephenButtolph]

Once we have a coreth rc + finalize the default values - this LGTM

[atinst]

Does this in a sense reduce network security?