Moving diagnostics into a service (#14832)

* Moving diagnostics into a service

* Fixing golint checks

* Fixing tests

* Renaming from diagnostics to telemetry

* Adding missing files

* Initializing telemetry earlier in the server startup

* Fixing tests

* Adding a log for the telemetryID initialization error

* Addressing PR review comments

* Fixing merge problem

* Removing some extra Diagnostics mentions

* Making tests pass

app/app.go

@@ -127,12 +127,8 @@ func (a *App) initJobs() {
 	a.srv.Jobs.Schedulers = a.srv.Jobs.InitSchedulers()
 }
 
-func (a *App) DiagnosticId() string {
-	return a.Srv().diagnosticId
-}
-
-func (a *App) SetDiagnosticId(id string) {
-	a.Srv().diagnosticId = id
+func (a *App) TelemetryId() string {
+	return a.Srv().TelemetryId()
 }
 
 func (s *Server) HTMLTemplates() *template.Template {
@@ -374,8 +370,8 @@ func (a *App) NotifyAndSetWarnMetricAck(warnMetricId string, sender *model.User,
 			}
 			bodyPage.Props["SiteURLHeader"] = T("api.templates.warn_metric_ack.body.site_url_header")
 			bodyPage.Props["SiteURL"] = a.GetSiteURL()
-			bodyPage.Props["DiagnosticIdHeader"] = T("api.templates.warn_metric_ack.body.diagnostic_id_header")
-			bodyPage.Props["DiagnosticIdValue"] = a.DiagnosticId()
+			bodyPage.Props["TelemetryIdHeader"] = T("api.templates.warn_metric_ack.body.diagnostic_id_header")
+			bodyPage.Props["TelemetryIdValue"] = a.TelemetryId()
 			bodyPage.Props["Footer"] = T("api.templates.warn_metric_ack.footer")
 
 			warnMetricStatus, warnMetricDisplayTexts := a.getWarnMetricStatusAndDisplayTextsForId(warnMetricId, T)