fix(inputgroup): Prevent infinite re-render loop in Leading/TrailingItems

[sentry]

This PR addresses the "Maximum update depth exceeded" error occurring in `InputGroup.LeadingItems` and `InputGroup.TrailingItems`.

Problem:
The useLayoutEffect in these components included children in its dependency array. When the parent InputGroup re-rendered, children would often receive a new object identity, even if its content was visually the same. This triggered the useLayoutEffect to call setLeadingWidth or setTrailingWidth, which in turn caused the parent InputGroup to re-render, creating an infinite loop.

Solution:

1. Replaced children dependency with ResizeObserver: The useLayoutEffect now initializes a ResizeObserver to monitor the actual offsetWidth of the ref.current element. This ensures that the effect only triggers when the physical dimensions of the leading/trailing items change, rather than when the children prop's reference changes.
2. Simplified width measurement: Removed the reliance on entries[0]?.borderBoxSize[0]?.inlineSize as it caused issues in JSDOM (Jest tests). Instead, el.offsetWidth is used directly within the ResizeObserver callback, which is simpler and more robust across environments.
3. Proper cleanup: The ResizeObserver is disconnected when the component unmounts to prevent memory leaks.

This change ensures that setLeadingWidth and setTrailingWidth are only called when truly necessary, resolving the infinite re-render loop.

Legal Boilerplate

Look, I get it. The entity doing business as "Sentry" was incorporated in the State of Delaware in 2015 as Functional Software, Inc. and is gonna need some rights from me in order to utilize my contributions in this here PR. So here's the deal: I retain all rights, title and interest in and to my contributions, and by keeping this boilerplate intact I confirm that Sentry can use, modify, copy, and redistribute my contributions, under Sentry's choice of terms.

Fixes JAVASCRIPT-3AYS

_{Comment @sentry <feedback> on this PR to have Autofix iterate on the changes.}

[github-actions]

Story previews

Preview the stories changed in this PR on the Vercel deployment:

• app/components/core/input/input.mdx
• app/components/core/input/inputGroup.mdx

_{Preview deployment: https://sentry-dnj04fi4c.sentry.dev}