Checkout Type can somehow sometimes be empty

[spencerrlongg]

Description

Early WIP

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Test Configuration:

• PHP version: 8.1
• MySQL version: 8.2

[shortcut-integration]

This pull request has been linked to Shortcut Story #24173: Checkout Type can somehow sometimes be empty.

[what-the-diff]

PR Summary

• Removal of assigned_to field in StoreAssetRequest.php
  The assigned_to field, previously included in a combining operation in the prepareForValidation function, has been removed. This alteration simplifies the validation process.

• Conditional Check added in AssetObserver.php
  A clause was introduced in AssetObserver.php to check the existence of assigned_to in $attributesOriginal. This correction ensures the proper functioning of the store method in Api/AssetsController - improving our API's reliability and performance.