Fixed custom field defaults being prematurely updated

[marcusmoore]

Description

This PR fixes an issue where attempting to update an asset model but getting a validation error still updated custom field default values even though the user is redirected back to the form:

custom.field.validation.issue.mp4

I manually disabled required for the name input to demonstrate the issue above.

The issue was we were updating the custom field value defaults before calling $model->save() and a failure at model level validation means the user would be redirected back but the defaults had already been updated.

We could probably update and utilize the StoreAssetModelRequest here but I found this as part of other work I'm doing and didn't want to get too distracted.

Type of change

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

[what-the-diff]

PR Summary

• Optimized Asset Model Updation
  The asset model saving process has been enhanced. We no longer remove custom fields before saving. Now, conditional code will decide whether to assign default field values based on the input received. This leads to more efficient and intelligent saving processes. Additionally, we are only moving to the next step if the model's 'End of life' attribute has been altered.

• Refined Testing Methods
  Improvements made to our testing methods using the 'CustomField' and 'CustomFieldset' models. The 'asset model storage' test now incorporates an updated 'PUT' method test. Also, new tests have been added to check for validation errors and updating of default field values. Special attention has been given to affirm that default field values remain constant even when a validation error occurs. They can also be updated if required. This refined testing process assures the stability and integrity of our application.