Remove id from table used for the row numbers

The fullscreenTable component has 2 layers to the
table you see onscreen:
1. the actual data table
2. a clone, with only the first column showing,
   that sits on top so the row numbers stay in
   place while you scroll

Table 1. has an id attribute on its caption. The
region wrapping it has an aria-describedby
attribute with the id as its value. This makes the
caption the description for the region.

This isn't needed for the clone and
makes the HTML invalid because ids should be
unique.

This removes the id from the cloned table.

app/assets/javascripts/fullscreenTable.js

@@ -51,6 +51,9 @@
             .removeClass('fullscreen-scrollable-table')
             .removeAttr(attributesForFocus)
             .attr('aria-hidden', true)
+            .find('caption')
+            .removeAttr('id')
+            .closest('.fullscreen-fixed-table')
         )
         .append(
           '<div class="fullscreen-right-shadow" />'