fix(dropdowns.next): `Combobox` with `isBare` option never shows horiz scrollbar to preserve styling

[ze-flo]

Description

The styling of <Combobox isBare> would break for users with OS settings set to always show scrollbars.

This update fixes it by setting the overflow-y of the input wrapper to visible when isBare is enabled. After fix:

isBare

isBare and isMultiSelectable

Checklist

• [ ] :ok_hand: design updates will be Garden Designer approved (add the designer as a reviewer)
• [x] :globe_with_meridians: demo is up-to-date (npm start)
• [ ] :arrow_left: renders as expected with reversed (RTL) direction
• [ ] :metal: renders as expected with Bedrock CSS (?bedrock)
• [x] :guardsman: includes new unit tests. Maintain existing coverage (always >= 96%)
• [ ] :wheelchair: tested for WCAG 2.1 AA accessibility compliance
• [x] :memo: tested in Chrome, Firefox, Safari, and Edge