By Toby Sterling, Caroline Pailliez and Tim Hepher AMSTERDAM/PARIS/DOHA (Reuters) – After 21 years as a service agent at Air France, Karim Djeffal left his job during the COVID-19 pandemic to start his own job-coaching consultancy. “If this doesn’t work out, I won’t be going back to the aviation sector,” says the 41-year-old bluntly. “Some shifts started at 4 a.m. and others ended at midnight. It could be exhausting.” Djeffal offers a taste of what airports and airlines across Europe are up against as they race to hire thousands to cope with resurgent demand, dubbed “revenge travel” as people …