client: fix invalid node name pattern regex

[andresilva]

See https://gitlab.parity.io/parity/mirrors/polkadot/-/jobs/3206771.

polkadot companion: https://github.com/paritytech/polkadot/pull/7484

(the companion above is fake, needed to unlock ci)

[michalkucharczyk]

Are other protocols' prefixes fine (like 'wss://')?

[bkchr]

Are other protocols' prefixes fine (like 'wss://')?

In the end this entire check here is useless anyway, because everyone could send whatever they want to the telemetry backend. So, this here is just some kind of sanity check.

[bkchr]

bot merge force