Dropdown keyboard accessibility appears to be broken

[sydk-adhoc]

Describe the bug
From the documentation

When the Dropdown is open ...
If the same character is typed in succession, visual focus cycles among the options starting with that character.

This is not happening, AFAICT. We are experiencing this issue in MCT since upgrading to MGov CMSDS v10

To Reproduce
Steps to reproduce the behavior:

1. Go to the CMSDS docs or Storybook for Dropdown, or, e.g., https://healthcare.gov/create-account (state dropdown)
2. Use the keyboard, only, to navigate to a dropdown and open with the down arrow key
3. Type any character that matches the beginning value of one of the options that has sibling options that start with the same character
4. Focus goes to the first option that begins with that character
5. Keep typing that character to cycle through the options (e.g., "M" for states that begin with "M")
6. Does not cycle through options

Expected behavior
Cycles through options that begin with the same character

Screenshots
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Desktop (please complete the following information):

• macOS Sequoia
• Safari, Chrome, Firefox
• Latest

Smartphone (please complete the following information):
N/A (no keyboard)

Additional context
Add any other context about the problem here.