[Read-only Inputs]: Update border-bottom color

[aagonzales]

After our final review with Devin and team we decided to make a final adjustment to input field's border-bottom color. It originally used $border-strong but should now be using $border-subtle.

Components to update:

• Date picker
• Dropdown
• Combo Box
• Multi-select
• Number input
• Select
• Text area
• Text input
• Time picker

Spec

[tw15egan]

Two things I've run into:

There is no readonly variant for Search.

FluidCombobox has some issues when setting readOnly (it is still active). All others look OK