Cleanup webhook edit form

What does this MR do and why?

This MR does cleanup the Webhook edit forms:

• Remove 2 column layout
• Use password field for Token (System Hook)

Follow-up to Webhook settings: Change to one column layout (!124522 - merged)

Screenshots or screen recordings

Before	After
Project Webhook	Project Webhook
Group Hook	Group Hook
System Hook	System Hook

How to set up and validate locally

1. Webhook
   1. Go to Webhook settings: http://gdk.test:3000/flightjs/Flight/-/hooks
   2. Create a new Hook
   3. Edit Hook
2. Group Hook
   1. Go to Group Hook settings: http://gdk.test:3000/groups/flightjs/-/hooks
   2. Create a new Hook
   3. Edit Hook
3. System Hook
   1. Go to System Hook settings: http://gdk.test:3000/admin/hooks
   2. Create a new Hook
   3. Edit Hook

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to UX Paper Cuts 16.2 → Settings UI (#398215 - closed)