sidebar: Fix sidebar-route-info alignment

time-info was pushing distance-info with margin, that can break the
alignment when time-info's length change.

The reason to use the sidebar-route-info-wrapper GtkGrid was to avoid
a visual glitch in the map view caused when we attempt to expand
horizontally a direct child of a sidebar's container.

https://bugzilla.gnome.org/show_bug.cgi?id=736166