chore(logme): drive-by fix remove unused const

Author: j1n-o9r

internal/cmd/logme/instance/update/update.go

@@ -34,7 +34,6 @@ const (
 	metricsFrequencyFlag     = "metrics-frequency"
 	metricsPrefixFlag        = "metrics-prefix"
 	monitoringInstanceIdFlag = "monitoring-instance-id"
-	pluginFlag               = "plugin"
 	sgwAclFlag               = "acl"
 	syslogFlag               = "syslog"
 	planIdFlag               = "plan-id"