This fix ensures that if the last focusable element in a popover container is a radio button, that the tab sequence is not affected once focus is outside of the container

fixes #7067

Proposed behaviour

Current behaviour

Checklist

• Commits follow our style guide
• Related issues linked in commit messages if required
• Screenshots are included in the PR if useful
• All themes are supported if required
• Unit tests added or updated if required
• Playwright automation tests added or updated if required
• Storybook added or updated if required
• Translations added or updated (including creating or amending translation keys table in storybook) if required
• Typescript d.ts file added or updated if required
• Related docs have been updated if required

QA

• Tested in provided StackBlitz sandbox/Storybook
• Add new Playwright test coverage if required
• Carbon implementation matches Design System/designs
• UI Tests GitHub check reviewed if required

Additional context

N/A

Testing instructions

Steps to reproduce
Using the new With Radio Button example:

• Press TAB key until you reach the with Radio children button.
• Press ENTER to open the popover container.
• Press TAB key until the last element of the list.
• Press TAB key.
• Focus should move to button next to the popover container's opening button.

There should also be no functional regressions or changes to the other PopoverContainer examples.