Blender Git Loki

CleanUp: DrawManager Balanced alloc/free of surface_per_mat cache

The alloc was done in the init, but the free was done in the discard.
As discarding can happen more often there were some unneeded if
statements to work around use after free.

This patch moves the free to the `mesh_batch_cache_clear` and removes
the if statements to check for use after free.