ST. PETERSBURG, Fla. — A federal judge’s decision to strike down a national mask mandate was met with cheers on some airplanes but also concern about whether it’s really time to end one of the most visible vestiges of the COVID-19 pandemic.The major airlines and many of the busiest airports rushed to drop their requirements on Monday after the Transportation Security Administration announced it wouldn’t enforce a January 2021 security directive that applied to airplanes, airports, taxis and other …