Remove fields deprecated in AvalancheGo v1.11.11

[Nuttymoon]

The following fields were deprecated in AvalancheGo v1.11.11:

• info.peers.observedSubnetUptimes
• platform.getCurrentValidators.connected

This PR makes the connected field optional and removes the observedSubnetUptimes field.

[richardpringle]

@Nuttymoon, the clippy errors seem easy enough to fix, but I'm not sure if I can say the same about the e2e test.

This is the line that's getting hit:
https://github.com/ava-labs/avalanche-rs/blob/main/tests/avalanche-e2e/src/x/simple_transfers.rs#L334

[Nuttymoon]

@richardpringle thanks for the quick review!

I fixed both issues. Clippy was easy indeed.

For the e2e test error, it comes from changes in Prometheus metrics introduced here ava-labs/avalanchego#2990 and here ava-labs/avalanchego#3053. avalanche_X_vm_avalanche_base_txs_accepted has been replaced by avalanche_avm_txs_accepted{chain="X",tx="base"}.

[Nuttymoon]

I am now encountering another issue with the e2e C-Chain tests in tests/avalanche-e2e/src/c/simple_transfers.rs. The following error is raised: transaction type not supported: type 2 rejected, pool not yet in Berlin which is super weird given that Berlin is a 2021 upgrade of the EVM. I tried playing around with the tx construction (e.g. commented .urgent()) and ended up with this other error: failed to send_transaction 'custom error: EIP-1559 not activated' which is weird in the same fashion.

[Nuttymoon]

@gyuho as expected, the tests failed with the error I mentioned above. No idea how to resolve it.