refactor: Remove unused server timezone seeder and related code

app/Models/InstanceSettings.php

@@ -37,6 +37,30 @@ class InstanceSettings extends Model implements SendsEmail
         );
     }
 
+    public function updateCheckFrequency(): Attribute
+    {
+        return Attribute::make(
+            set: function ($value) {
+                return translate_cron_expression($value);
+            },
+            get: function ($value) {
+                return translate_cron_expression($value);
+            }
+        );
+    }
+
+    public function autoUpdateFrequency(): Attribute
+    {
+        return Attribute::make(
+            set: function ($value) {
+                return translate_cron_expression($value);
+            },
+            get: function ($value) {
+                return translate_cron_expression($value);
+            }
+        );
+    }
+
     public static function get()
     {
         return InstanceSettings::findOrFail(0);