Repro steps:
1. Import the attached project and open the repro scene
2. Enter play mode
3. Observe that both the particles and the capsule (output mesh) are blurred.

Expected outcome:
- Only the moving particles to receive motion blur

Notes:
- Looks like the particle motion vectors are being used for the output mesh
- We also don't have a way of enabling/disabling motion vectors at the Output Mesh level (it can only be done in the shader, which means separate shaders need to be used to just toggle motion vectors on a per-mesh-output basis)