Fix carousel retry link refreshing all carousels

[jimchamp]

Follows #11028

Fixes regressions annotated here and here.

Technical

Testing

Screenshot

Stakeholders

[Copilot]

Pull Request Overview

This PR refactors the lazy carousel JavaScript code to improve error handling and code quality. The changes eliminate jQuery usage in favor of vanilla JavaScript and add a null check for an optional DOM element.

Key Changes

• Replaced jQuery event listener with vanilla JavaScript addEventListener for the retry button
• Added null safety check for the .lazy-carousel-fallback element before manipulating its class list
• Updated comment from plural "listeners" to singular "listener" to match the actual behavior

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[Copilot]

Potential null dereference if .retry-btn element is not found. Add a null check before calling addEventListener, similar to the null check added for carouselFallbackElem in the handleRetry function.

Suggested change

	retryElem.addEventListener('click', (e) => {
	e.preventDefault()
	handleRetry(elem);
	})
	if (retryElem) {
	retryElem.addEventListener('click', (e) => {
	e.preventDefault()
	handleRetry(elem);
	})
	}

[cdrini]

Great catch! Lgtm. Putting on testing now for a test, but code makes sense to me 👍

[cdrini]

Tried going offline midway through https://testing.openlibrary.org/collections/the_haunted_library , and confirmed the retry link only reloaded one carousel 👍