A prostrate rosemary. Wandering Jew, Silver ponyfoot, wooly stemodia, Sedum palmerii ( not a vine but cascades nicely), Ditany of crete, ornamental oreganoes ( Kent beauty and relatives). Some of these are cascading plants not vines.

Prostrate rosemary might be the best idea, rosemary typically doesn't invade. Wandering Jew is pretty invasive and mine dies back to the roots every winter. The silver ponyfoot I have spread very well but has died back to the roots (I hope).

Most vines and spreading plants are going to want to grow back into the garden as well as over the wall. Mother-of-thyme spreads and will cascade over the edge of a pot but I don't know if it would try to take over the entire garden. Could you do a combination of a cascading plant on top and a short plant at the bottom of the wall?

I like confederate jasmine. It's not invasive and when it blooms it smells great. It does grow fast when established but is easy to control. Evergreen. Only drawback to me is when cut has a milky, sticky sap.

I put it along a trellis/fence between my yard and the neighbors. Also have it on a trellis next to my pool as a privacy screen.

How about callirhoe involcrata