Refactor Layout Builder Form Alter with a better logic

Problem/Motivation

I've noticed a problem with the code in varbase_layout_builder_form_alter. Currently, it's being executed for all form renders, but it should only be executed specifically for the layout builder form.

Steps to reproduce

• N/A

Proposed resolution

1. Review the existing code in `varbase_layout_builder_form_alter` and identify the section that needs to be limited to the layout builder form.
2. Introduce a conditional check to ensure that the code is only executed when the layout builder form is being processed.
3. Test the updated code thoroughly to ensure it functions correctly and doesn't affect other forms or functionalities.

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ✅ Testing to ensure no regression
• ✅ Automated unit/functional testing coverage
• ➖ Developer Documentation support on feature change/addition
• ➖ User Guide Documentation support on feature change/addition
• ✅ Accessibility and Readability
• ✅ Code review from 1 Varbase core team member
• ✅ Full testing and approval
• ✅ Credit contributors
• ✅ Review with the product owner
• ✅ Update Release Notes and Update Helper on new feature change/addition
• ✅ Release varbase-9.0.14, varbase_layout_builder-10.0.28, Varbase 10.0.0-beta1, varbase_layout_builder-10.1.0-alpha4

Varbase update type

• ✅ No Update
• ➖ Optional Update
• ➖ Forced Update
• ➖ Forced Update if Unchanged

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• Issue #3367015 by abu-zakham: Refactored Layout Builder Form Alter with a better logic