Fix autocomplete not having y-scroll
Fix autocomplete not having y-scroll

After changing flex-order the children did not have a max-height which
ended up in the child growing to outside of the screen instead of
being properly constrained.

Fix https://github.com/vector-im/element-web/issues/18997

matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk