Secondary beacon effect remains when switching primary effect

The bug

When you have selected a primary and a secondary effect (that is not regeneration), you can keep that effect even after you switch the primary effect. This allows a beacon to provide two different primary effects.

How to reproduce

1. Activate a beacon with a complete pyramid.

   /fill ~-4 ~-1 ~-4 ~4 ~-4 ~4 minecraft:iron_block
   /setblock ~ ~ ~ minecraft:beacon

2. Select Speed as the primary effect and Speed 2 as the secondary effect
3. Change the primary effect to Resistance without changing the secondary effect
4. Wait for the Speed 2 effect to run out
   Notice that you have both Speed and Resistance. Note that the beacon interface shows that the secondary effect is deactivated.