Bug 6032: Give biblio register and shadow sane default max sizes

Bug 6032: Give biblio register and shadow sane default max sizes

The out-of-the-box maximum size for the biblio register and shadow stores is
4GB, which is much too small for even medium sized libraries. This makes the
default maximum 20GB, which should be enough for even most large libraries.

Signed-off-by: Ian Walls <ian.walls@bywatersolutions.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
(cherry picked from commit 2b71959a88029d9b948e13ad2f1f863fad8c44d6)

Signed-off-by: Chris Nighswonger <chris.nighswonger@gmail.com>