The checkbox should not be disabled for the custom attributes

[Sanjaybhattwebkul]

CRM Version: V1.2.2

Steps To reproduce--

1. Log in as Admin/User.
2. Click on the web form inside the setting tab.
3. Try to create a new webform
4. Add new attributes.
5. Try to check the required checkbox

Expected result: The checkbox should not be disabled for the custom attributes

Actual result: The checkbox is disabled for the custom attributes. Please find the below screenshot.