Attach cluster info to slow log and metrics

[iosmanthus]

Feature Request

Is your feature request related to a problem? Please describe:

While handling multiple clusters with a single client, we need some information to distinguish them in metrics and slow log outputs. Otherwise, it's hard to tell which cluster is dubious.

Describe the feature you'd like:

• Attach cluster_id and pd_addresses properties to slow log. [to #556] slowlog: attach cluster_id and pd_addresses to slow log properties #557
• Attach cluster_id label to metrics. [to #556] metrics: attach cluster label to metrics #558

[github-actions]

This issue is stale because it has been open 30 days with no activity.