Use a transaction when adding a beatmap
Use a transaction when adding a beatmap

Fixes flakey unit test.
peppy/osu-new,UselessToucan/osu,peppy/osu,peppy/osu,2yangk23/osu,Nabile-Rahmani/osu,ppy/osu,EVAST9919/osu,2yangk23/osu,johnneijzen/osu,peppy/osu,smoogipoo/osu,EVAST9919/osu,smoogipooo/osu,naoey/osu,johnneijzen/osu,ZLima12/osu,Damnae/osu,Frontear/osuKyzer,NeoAdonis/osu,smoogipoo/osu,UselessToucan/osu,NeoAdonis/osu,naoey/osu,ppy/osu,NeoAdonis/osu,DrabWeb/osu,Drezi126/osu,ppy/osu,smoogipoo/osu,DrabWeb/osu,ZLima12/osu,DrabWeb/osu,naoey/osu,UselessToucan/osu