* Add a GaugeVec for enabled plugins monitoring.
Signed-off-by: Jiacheng Xu <xjcmaxwellcjx@gmail.com>

* Add server label and zone label for enable_plugin matric.

* Add a test for PluginEnabled metric

* Add description for enabledPlugin metric.

* Change the description for the enabledPlugin metric.

* Reset the enabledPlugin metric when restart the server.

* Add the bug session for enabledPlugin metric.

* Remove the resolveTCPAddr