codegen: is_codegen_valid_for doesn't work as expected for "trimmed metadata"

[niklasad1]

1. Generate metadata/codegen

$ subxt metadata --url wss://rpc.polkadot.io --pallets "ElectionProviderMultiPhase,System" -f bytes > metadata.scale

2. Connect to the same node and compare the metadata (this calls "is_codegen_valid_for" internally)

$ ./target/debug/staking-miner --uri wss://rpc.polkadot.io info
Remote_node:
{
  "spec_name": "polkadot",
  "impl_name": "parity-polkadot",
  "spec_version": 9431,
  "impl_version": 0,
  "authoring_version": 0,
  "transaction_version": 24,
  "state_version": 0
}
Compatible: NO

If one just generates "untrimmed metadata" it works as expected.

[jsdw]

Oh interesting, it def should work for trimmed metadata, so I geuss there's a bug somewhere!