EuiContextMenu right now is designed to render inside of a popover (but doesn't strictly need to be). With this, it relies on the consuming developer to put it in EuiPopover which can provide some flexibility in styling but also can provide some headache as demonstrated when we were improving our focus states.

It's not immediately apperent which props should go on the ContextMenu and which should go on the Popover. I think we can get the same flexibility we currently have just by allowing EuiContextMenu to take a popoverProps prop which will pass everything through while setting up a sensible default for consumers while also relieving some boilerplate from every usage.