feat: add --metrics [flag] to forest

[hanabi1224]

Summary of changes

Adding an option to disable metrics endpoint (just like for RPC endpoint) to facilitate writing simple test for #3593

Changes introduced in this pull request:

• add --metrics [flag] to forest to control the availability of the Prometheus server

Reference issue to close (if applicable)

Closes

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

[LesnyRumcajs]

The usage now would be --metrics false and --metrics true, while a possibility, would never be used. How about --disable-metrics boolean? Or --no-metrics.

[hanabi1224]

The usage now would be --metrics false and --metrics true, while a possibility, would never be used. How about --disable-metrics boolean? Or --no-metrics.

@LesnyRumcajs It makes sense, using --metrics [true|false] is to align with the existing --rpc [true|false] option. Do you suggest changing only this one or both?

[LesnyRumcajs]

We should change both for consistency, but in separate PRs.

[hanabi1224]

We should change both for consistency, but in separate PRs.

@LesnyRumcajs Changed to --no-metrics

[LesnyRumcajs]

A bit of code-golf if you wish

Suggested change

	if self.no_metrics {
	cfg.client.enable_metrics_endpoint = false;
	} else {
	cfg.client.enable_metrics_endpoint = true;
	if let Some(metrics_address) = self.metrics_address {
	cfg.client.metrics_address = metrics_address;
	}
	}
	cfg.client.enable_metrics_endpoint = !self.no_metrics;
	cfg.client.metrics_address = self.metrics_address.unwrap_or(cfg.client.metrics_address);