AccordionItemHeader slot not taking full width

[Akshay090]

Issue Summary:
The AccordionItemHeader slot element does not take the full width, even when a width of 100% is applied.

Description:
This issue appears to be caused by the Box component that wraps the slot element, which does not have the appropriate styles. The wrapping Box component may be redundant. I have removed it, and the base accordion seems to be working fine without it.

PR Link: #2357

Link to Example reproducing issue : https://stackblitz.com/edit/fu9qww