The bell is a warning device, not a way of asking to pass. Danish law allows a sound signal only when it is needed to prevent or avert danger, so locals no more ring to overtake than they would honk to overtake in a car - they simply pass on the left with room.
If someone does ring behind you, read it as a warning rather than road rage: keep your line or ease right. No offence is meant and none should be taken.
Every bike in Denmark must have a bell, but the bell is a safety device rather than a piece of etiquette. The law allows a sound signal only when it is necessary to prevent or avert danger, and only for as long as necessary - the same reason nobody sounds a car horn here just to get past. Ringing at a slower rider to make them move is not the local custom, and it is not what the bell is for.
So overtake the ordinary way: glance over your left shoulder, pull out, pass on the left with room, and come back in once you are clear. Save the bell for the moments it was made for - someone stepping into the cycle track without looking, a rider drifting across your line, a car door starting to open. And if a bell goes off behind you, hear it as a warning rather than an insult: hold a steady line or ease gently to the right and let them through.