The gametest effect_durations_longer_first uses regular potions instead of splash potions

The gametest "effect_durations_longer_first" from the category MobTests uses one regular potion of regeneration and one regular potion of regeneration II when it should use splash potions instead.

How to reproduce:

1. Open a world with gametest features enabled
2. Run the command "/gametest run mobtests:effect_duration_longer_first"
3. Wait until the test is finished.

Expected result:

The test uses splash potions.

Actual result:

The test uses regular potions and therefore always gives a negative result.