MM-27199 - Add metrics to MM server for total enabled user count (#15116)

* Add metrics to MM server for total enabled user count and include installation ID from a new env var

* diagnostics context

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

model/job.go

@@ -20,6 +20,7 @@ const (
 	JOB_TYPE_MIGRATIONS                     = "migrations"
 	JOB_TYPE_PLUGINS                        = "plugins"
 	JOB_TYPE_EXPIRY_NOTIFY                  = "expiry_notify"
+	JOB_TYPE_ACTIVE_USERS                   = "active_users"
 
 	JOB_STATUS_PENDING          = "pending"
 	JOB_STATUS_IN_PROGRESS      = "in_progress"
@@ -61,6 +62,7 @@ func (j *Job) IsValid() *AppError {
 	case JOB_TYPE_MIGRATIONS:
 	case JOB_TYPE_PLUGINS:
 	case JOB_TYPE_EXPIRY_NOTIFY:
+	case JOB_TYPE_ACTIVE_USERS:
 	default:
 		return NewAppError("Job.IsValid", "model.job.is_valid.type.app_error", nil, "id="+j.Id, http.StatusBadRequest)
 	}