UI: Unify how we detect abort errors

[DingoEatingFuzz]

As part of the Ember 3.20 and related dependency upgrades, the existing error instanceof AbortError check became insufficient.

With some research, I think we can find a new way to handle this issue with a single conditional.

nomad/ui/app/adapters/watchable.js

Lines 58 to 68 in 4e0e33e

	const signal = get(snapshot || {}, 'adapterOptions.abortController.signal');
	return this.ajax(url, 'GET', {
	signal,
	data: params,
	}).catch(error => {
	if (error instanceof AbortError || error.name == 'AbortError') {
	return;
	}
	throw error;
	});
	}

Introduced in #9912