[MM-59060] Remove pre release features section from advanced section of user settings (#27608)

server/tests/test-config.json

@@ -54,7 +54,6 @@
         "EnableUserStatuses": true,
         "ExperimentalEnableAuthenticationTransfer": true,
         "ClusterLogTimeoutMilliseconds": 2000,
-        "EnablePreviewFeatures": true,
         "EnableTutorial": true,
         "EnableOnboardingFlow": true,
         "ExperimentalEnableDefaultChannelLeaveJoinMessages": true,