flake8 uicfg

[uicfg] Remove unpredictability from autoform_section initialization It was attempting to guess smart default values by looking at the opposite relation (neg_role), but depending on the (random) ordering of the schema, it may or may not have been set yet, leading to unpredictable result with varying hash seed. Remove those fuzzy lookup all at once, it may change some (unreliable) things in your app but at least it's still a bit easier to explain. Closes #16272968

[schema/optimization] Wrap rql expressions into EXISTS node when checking individual permissions Some RQL expression may retrieve several results. It makes sense to wrap them into an EXISTS node to optimized things a bit. This is already done by security insertion of 'read' rql expressions.