Remove unnecessary message prop from Snackbar

When the Snackbar has children, the message prop is ignored, so we can
remove it from here to simplify the component.

cf. https://github.com/mui-org/material-ui/blob/master/packages/material-ui/src/Snackbar/Snackbar.js#L247

Signed-off-by: Mike Lewis <mtlewis@users.noreply.github.com>

packages/core/src/components/AlertDisplay/AlertDisplay.tsx

@@ -46,11 +46,7 @@ export const AlertDisplay = () => {
   };
 
   return (
-    <Snackbar
-      open
-      message={firstMessage.message.toString()}
-      anchorOrigin={{ vertical: 'top', horizontal: 'center' }}
-    >
+    <Snackbar open anchorOrigin={{ vertical: 'top', horizontal: 'center' }}>
       <Alert
         action={
           <IconButton