[web][photos] Fix mobile upload button hover & position

The hover and ripple effects and the positioning were off on the mobile upload button, because the `.mobile-button` class used the wrong class to let the element appear again. It used `display: block`, but the MUI IconButton actually has `display: inline-flex`, which will also fix the wrong height of the button.

See https://github.com/mui/material-ui/issues/33020

web/apps/photos/src/components/Upload/UploadButton.tsx

@@ -17,7 +17,7 @@ const Wrapper = styled("div")<{ $disableShrink: boolean }>`
         !$disableShrink &&
         `@media (max-width: 624px) {
         & .mobile-button {
-            display: block;
+            display: inline-flex;
         }
         & .desktop-button {
             display: none;