Remove getRealtimeHost from CompleteDefaults

It’s not used, and the property doesn’t actually exist on the Defaults
const (type assertion means compiler doesn’t catch it).

src/common/lib/util/defaults.ts

@@ -44,7 +44,6 @@ type CompleteDefaults = IDefaults & {
   getFallbackHosts(options: NormalisedClientOptions): string[];
   getHosts(options: NormalisedClientOptions, ws?: boolean): string[];
   checkHost(host: string): void;
-  getRealtimeHost(options: ClientOptions, production: boolean, environment: string): string;
   objectifyOptions(
     options: undefined | ClientOptions | string,
     allowKeyOrToken: boolean,