Add a test to ensure fair subnet validator service limits

[hexfusion]

The cost of entry for subnets is fairly high which could motivate validator owners to service many subnets. We should better understand the upper bounds of what a system will support and ensure our rules for benching are correct/fair. This issue covers ensuring these tests and proper metrics/alerting exist.

benching logic:

avalanchego/snow/networking/router/chain_router.go

Lines 540 to 542 in 14b8c98

	// This will disconnect the node from all subnets when issued to P-chain.
	// Even if there is no chain in the subnet.
	msg := message.InternalDisconnected(nodeID)

uptime loss:

avalanchego/vms/platformvm/vm.go

Line 434 in 61e7aa6

if err := vm.uptimeManager.Disconnect(nodeID); err != nil {

[github-actions]

This issue has become stale because it has been open 60 days with no activity. Adding the lifecycle/frozen label will cause this issue to ignore lifecycle events.

[koko1123]

hey @patrick-ogrady is this issue still open? I can pick this up, I want to learn about the codebase. is there a discord I can join?

[github-actions]

This issue has become stale because it has been open 60 days with no activity. Adding the lifecycle/frozen label will cause this issue to ignore lifecycle events.