Hide pre-release features section of advanced settings pane. (#7847)

config/default.json

@@ -51,7 +51,8 @@
         "EnableUserTypingMessages": true,
         "EnableChannelViewedMessages": true,
         "EnableUserStatuses": true,
-        "ClusterLogTimeoutMilliseconds": 2000
+        "ClusterLogTimeoutMilliseconds": 2000,
+        "EnablePreviewFeatures": true
     },
     "TeamSettings": {
         "SiteName": "Mattermost",

model/config.go

@@ -205,6 +205,7 @@ type ServiceSettings struct {
 	EnableUserStatuses                       *bool
 	ClusterLogTimeoutMilliseconds            *int
 	CloseUnusedDirectMessages                *bool
+	EnablePreviewFeatures                    *bool
 }
 
 func (s *ServiceSettings) SetDefaults() {

utils/config.go

@@ -489,6 +489,7 @@ func getClientConfig(c *model.Config) map[string]string {
 	props["AllowEditPost"] = *c.ServiceSettings.AllowEditPost
 	props["PostEditTimeLimit"] = fmt.Sprintf("%v", *c.ServiceSettings.PostEditTimeLimit)
 	props["CloseUnusedDirectMessages"] = strconv.FormatBool(*c.ServiceSettings.CloseUnusedDirectMessages)
+	props["EnablePreviewFeatures"] = strconv.FormatBool(*c.ServiceSettings.EnablePreviewFeatures)
 
 	props["SendEmailNotifications"] = strconv.FormatBool(c.EmailSettings.SendEmailNotifications)
 	props["SendPushNotifications"] = strconv.FormatBool(*c.EmailSettings.SendPushNotifications)