Fix avatars vanishing on hover
Fix avatars vanishing on hover

Turns out the z-index was to make the avatar appear above the
EventTile_line even though it comes before in the DOM (it's
absolutely positioned to overlap with it). Instead, just put
it afterwards in the DOM.

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