Fix v5 regressions in tab dropdown functionality

[cpsievert]

Refs #33625 (fixes the 1st problem, at least)

I'd also be happy to help address the 2nd issue, but I'm not sure whether you'd prefer to just update the docs, or actually fix the Tab logic to support .dropdown-items wrapped in <li>

<ul class="dropdown-menu">
     <li><a class="dropdown-item" href="#">Action</a></li>
</ul>

To do the latter, looks as though we need to modify the 1st part of this logic to do something closer to const dropdownElement = element.parents(SELECTOR_DROPDOWN).find(CLASS_NAME_DROPDOWN_MENU)

bootstrap/js/src/tab.js

Lines 165 to 174 in db32b23

	if (element.parentNode && element.parentNode.classList.contains(CLASS_NAME_DROPDOWN_MENU)) {
	const dropdownElement = element.closest(SELECTOR_DROPDOWN)
	if (dropdownElement) {
	SelectorEngine.find(SELECTOR_DROPDOWN_TOGGLE)
	.forEach(dropdown => dropdown.classList.add(CLASS_NAME_ACTIVE))
	}
	element.setAttribute('aria-expanded', true)
	}

[GeoSot]

@cpsievert can you add a test too?

[GeoSot]

Thank you for you contibution @cpsievert
I would suggest to open another issue/PR for the second case, supporting ul > li > .dropdown-item