Radius scale of the particle system trigger doesn't seem to have any effect.

Repro steps:
1. Open the Bug_RadiusScale scene from the attached project.
2. Press play
3. Select Particle System from the hierarchy, open the trigger panel, and change the radius scale parameter.
4. Observe how there is no change in how many particles are affected by the trigger.

Expected outcome: a change in when particles hit the trigger based on the radius scale.

Notes:
- Visualization of radius scale (akin to the one in the Collision model) also pending integration.

Not a regression; new feature in 5.4.0b1