Blender Git Loki

Fix T88145: Dynamic Paint initial color using vertex color not working as expected

Mistake in {rBe48c4d73d378}.

Was using the vertex index as a lookup for the loop color (instead of
the loop index).
(Issue was not present in original D1429 btw).

Maniphest Tasks: T88145

Differential Revision: https://developer.blender.org/D11212