Bug 10811: (follow-up) use "local-number" rather than "Local-Number"

Bug 10811: (follow-up) use "local-number" rather than "Local-Number"

At present, the QueryParser search mode expects that search field names
and aliases are case-sensitive.  This may change (see bug 11353), but
for now, this patch ensures that the local-number searches used by
the KohaBiblio rule will work regardless of the value of the
UseQueryParser system preference.

To test:

[1] Use the KohaBiblio 999$c matching rule with UseQueryParser both
    on and off.  Verify that matching by biblionumber works correctly.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>