[MM-56904] Reduce the number of api requests made to fetch user information for GMs on page load (#27149)

* use new endpoint to fetch group members

server/channels/store/store.go

@@ -652,6 +652,7 @@ type PreferenceStore interface {
 	PermanentDeleteByUser(userID string) error
 	DeleteOrphanedRows(limit int) (deleted int64, err error)
 	CleanupFlagsBatch(limit int64) (int64, error)
+	DeleteInvalidVisibleDmsGms() (int64, error)
 }
 
 type LicenseStore interface {