LP1950345-Format the Current Hold Groups table in bootstrap opac

LP1950345-Format the Current Hold Groups table in bootstrap opac

This patch styles the Current Hold Groups table in bootstrap to be consistent
with other tables in the bootstrap catalog.  It fixes overlappling text
in cells.  It also fixes the column headings for small screens.  Previously
the headings on small screens were pulling from the css rules for the
holds history table.

To test:
1. create a couple of hold groups and add a patron to each group.  Make the
groups opac visible.
2. login to the opac as the patron to view the holds groups to which the
patron belongs.  Notice the table style with not margins or padding.
3. make your browser as small as possible to see the incorrect headings.
4. apply the patch.
5. repeat 2 and 3 to view the fix.

Signed-off-by: Garry Collum <gcollum@gmail.com>