Update the styling for invalid form fields

[afercia]

Splitting this out from #47018.

In a few places in the admin, a red border (actually a border and a box-shadow) are added to some form controls when submitting the form with some empty values.

The style of this red border still uses some transparency and doesn't match any longer with the new style used, for example, for the focus style which is a 'solid' border with no transparency.

For consistency, the red 'error' style should be updated. Here's a few places where the red error style can be checked:

• The Categories and Tags pages.
• The Edit Comment page, see the date and time small form under 'Submitted on'.
• Same for the Classic Editor Edit post page.
• The Menus page > create a new menu.

See attached screenshots.

[afercia]

Error and focus style shapes mismatch

[afercia]

55541.diff​

• Updates the red border style used for the invalid form fields.

To test:

• Check all the forms mentioned in this ticket description.
• Check the new red 'border' style matches the new 'solid' border pattern used for form fields.

[afercia]

Example of the new style