Add floating-ui to ButtonSetWithOverflow

[elycheea]

At smaller screen sizes (use containerWidth in Storybook to demonstrate), ButtonSetWithOverflow collapses to use MenuButton.

Verify that Carbon version with MenuButton floating UI is updated in our library. Blocked until @carbon/react adds support for floating ui to OverflowMenu.

Tasks

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1. Enable enable-v12-overflowmenu feature flag to ButtonSetWithOverflow overflow menus
2. Update tests if applicable

[elycheea]

floating-ui was been added to the new OverflowMenu. Will open an issue for adopting the v12 overflow menu.

[amal-k-joy]

Closing this as not planned.
As we analysed, ButtonSetWithOverflow component uses carbon MenuButton rather than Overflowmenu and
enable-v12-overflowmenu feature flag is not available for MenuButton.
Also we can explore more and adopt floating UI in the new PageHeader V2.