Update plugin id

[dmitryk-dk]

⚠️ Breaking Change: Plugin ID Updated
Update Note 1:
In the new version of the plugin, the plugin ID has been updated. The new plugin ID is victoriametrics-metrics-datasource. This is a breaking change: Grafana will treat this as a new plugin.

• You must update the allow_loading_unsigned_plugins field in the grafana.ini or defaults.ini configuration file.
  Example:

  allow_loading_unsigned_plugins = victoriametrics-metrics-datasource  

• If you are using provisioning, update the type field to victoriametrics-metrics-datasource in your provisioning configuration.
• After making these changes, you must restart the Grafana server for the updates to take effect.

Related issue: #233

[hagen1778]

Thanks!