Bug 36567: Get rid of Datetime warning in Circulation.t and dateexpiry.t

Bug 36567: Get rid of Datetime warning in Circulation.t and dateexpiry.t

Running either t/db_dependent/Circulation.t or t/db_dependent/Circulation/dateexpiry.t
cause following error to be dispalyed:

You are creating a DateTime object with a far future year (9999) and a time
zone (Europe/Helsinki). If the time zone you specified has future DST changes
this will be very slow.

Smallest allowed value is 4999, so we need to use that rather than 9999 in tests.

To test prove t/db_dependent/Circulation.t and t/db_dependent/Circulation/dateexpiry.t.

Sponsored-by: Koha-Suomi Oy
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Pedro Amorim <pedro.amorim@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>