MM-16378: revert plugin health check config removal (#11819)

* revert 4e5f6fcfbc

This reverts the configuration setting to disable plugin health checks, preferring instead to retain this functionality for advanced cases. In part, this was driven by the discovery that the health checks were failing on Windows, though that will be addressed separately.

Fixes: MM-16378

* simplify interval handling/logging

Also shutdown the job when plugins are altogether disabled.

app/diagnostics.go

@@ -597,6 +597,7 @@ func (a *App) trackConfig() {
 		"enable":                        *cfg.PluginSettings.Enable,
 		"enable_uploads":                *cfg.PluginSettings.EnableUploads,
 		"allow_insecure_download_url":   *cfg.PluginSettings.AllowInsecureDownloadUrl,
+		"enable_health_check":           *cfg.PluginSettings.EnableHealthCheck,
 	})
 
 	a.SendDiagnostic(TRACK_CONFIG_DATA_RETENTION, map[string]interface{}{

app/server.go

@@ -204,8 +204,14 @@ func NewServer(options ...Option) (*Server, error) {
 	// Start plugin health check job
 	pluginsEnvironment := s.PluginsEnvironment
 	if pluginsEnvironment != nil {
-		pluginsEnvironment.InitPluginHealthCheckJob()
+		pluginsEnvironment.InitPluginHealthCheckJob(*s.Config().PluginSettings.Enable && *s.Config().PluginSettings.EnableHealthCheck)
 	}
+	s.AddConfigListener(func(_, c *model.Config) {
+		pluginsEnvironment := s.PluginsEnvironment
+		if pluginsEnvironment != nil {
+			pluginsEnvironment.InitPluginHealthCheckJob(*s.Config().PluginSettings.Enable && *c.PluginSettings.EnableHealthCheck)
+		}
+	})
 
 	mlog.Info(fmt.Sprintf("Current version is %v (%v/%v/%v/%v)", model.CurrentVersion, model.BuildNumber, model.BuildDate, model.BuildHash, model.BuildHashEnterprise))
 	mlog.Info(fmt.Sprintf("Enterprise Enabled: %v", model.BuildEnterpriseReady))