Disable AVX optimizations for 32-bit composite ops

They cause artifacts and we don't have a fix yet :(

CCBUG:404133

Note from the committer:
This commit was initially made on krita/4.2 branch.
However between 4.2.1 and 4.2.2 the stable branch was
reconstructed, which caused all commits that were exclusively
on the previous krita/4.2 (and not on master) to be missing.

The previous commit hash: d3e4c3aa

Also regarding the artifacts: it never worked, optimization were
enabled during the creamy flow implementation, but they never should
be enabled until someone fix them properly.