fix(useScroll): evade edge case when window or document is Proxy

[MinatoHikari]

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As the VueUse audience continues to grow, we have been inundated with an overwhelming number of feature requests and pull requests. As a result, maintaining the project has become increasingly challenging and has stretched our capacity to its limits. As such, in the near future, we may need to slow down our acceptance of new features and prioritize the stability and quality of existing functions. Please note that new features for VueUse may not be accepted at this time. If you have any new ideas, we suggest that you first incorporate them into your own codebase, iterate on them to suit your needs, and assess their generalizability. If you strongly believe that your ideas are beneficial to the community, you may submit a pull request along with your use cases, and we would be happy to review and discuss them. Thank you for your understanding.

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Description

fix #3136

the e.target/target will never be equal to window.document/window when it is a Proxy.

Additional context

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🤖 Generated by Copilot at ab6806a

Refactor useScroll to use optional chaining and remove redundant checks. Improve readability and performance of getting scroll element and event target.

🤖 Generated by Copilot at ab6806a

• Simplify the logic for getting the scroll element and the event target by using the optional chaining operator (??) (link, link)