"trigger" entity events occur out of sequence order

The bug

The sequence entity event is supposed to run all of its entries in order, in situations where the order matters. However, trigger events included in the sequence ignore the order and always run last.

How to reproduce

1. Download and open the attached world. It contains a pig that, when hit with a wooden shovel, runs this event:

"sequence": [
   { "trigger": { "target": "self", "event": "big" } },
   { "add": { "component_groups": ["small"] } }
]

2. Hit the pig with the shovel

Expected result
The pig should turn small, since the small group was added second in the sequence, overwriting the big group added earlier.

Observed result
The pig turned large. The trigger happened last, even though it was defined to happen first in the sequence.