Remove required barrier for indirect dispatch safety check

[teoxoy]

The initial implementation (#5714) has to always insert a barrier to transition the destination buffer.

I attempted to alleviate this issue in 01dab26 (not on trunk) but that approach has a fundamental flaw (#5714 (comment)) - it assumes that command buffers are submitted in the same order that they have been created in.

We should find a way to avoid inserting the additional barrier (most likely at submit time).