On some drivers, the GLSL compiler doesn't reflect the omitted
`local_size_*` of a compute shader inside `gl_WorkGroupSize`.
This lead to the 2D size computation of 1D workgroups to become
0 which was bypassing the parallel reduction algorithms.
Ensuring `local_size_*` are always set fixes the issue.
For clarity, also fix the 1D shaders to not use `gl_WorkGroupSize.y`.
This also fix a copy paste error in the Metal backend.
This issue affected AMD drivers on Windows.
Rel #142046
Candidate for backporting to 4.5 LTS.
Pull Request: https://projects.blender.org/blender/blender/pulls/144056
16430b10f1