When editing a user and validation errors occur:

• Toast notification now shows actual error messages instead of empty string
• Inline errors now appear below custom User Profile attributes
• Errors are properly extracted and displayed for both single and multiple errors

The fix ensures that custom User Profile attributes (with 'attributes.' prefix) are handled correctly even when unmanaged attributes are enabled.

1. Toast notification with error message

Before:

• Toast showed an empty message ("The user has not been saved: ") when validation errors occurred.
• Inline validation errors did not appear below custom User Profile attributes when editing a user, even though they worked for standard fields like email.

After the fix:

• Toast displays the actual error message extracted from the server response, making it clear why the save failed.
• Inline errors now appear below custom User Profile attributes (e.g., customRequired), providing immediate feedback when required fields are empty or validation fails. This matches the behavior seen when creating a new user.

2. Toast notification with multiple error messages

3. Attributes Section

Before:

• Toast showed an empty message ("The user has not been saved: ") when validation errors occurred.
  After the fix:
• Toast displays the actual error message extracted from the server response, making it clear why the save failed.

Closes #44819