Issue #1650930 by mkalkbrenner, gidarai, daffie, JeroenT, murilohp, jungle,...

Issue #1650930 by mkalkbrenner, gidarai, daffie, JeroenT, murilohp, jungle, acbramley, shahankitb1982, anmolgoyal74, claudiu.cristea, klausi, super_romeo, ankithashetty, longwave, pooja saraah, sahil.goyal, mikeytown2, deviantintegral, mhavelant, elgandoz, catch, andypost, pounard, neclimdul, Damien Tournoud, Charlie ChX Negyesi, danblack, larowlan: Use READ COMMITTED by default for MySQL transactions