By Allison Lampert (Reuters) – Piles of luggage beside baggage belts in airports from Canada to Europe are driving further demand for ground handlers, and adding to summer travel chaos as airlines scramble to bring back workers lost during COVID-19. Once a cost-cutting and outsourcing target for aviation, ground handlers are now being offered raises, as frazzled passengers take to social media to complain about missing baggage. The hiring can’t come fast enough as a rebound in travel and badly-needed airline revenue this summer is being weighed by congestion, rising costs and labor strife, aft…