Bug 7728: Fix subs history end date consistency

Bug 7728: Fix subs history end date consistency

Without this patch, there is an inconsistency in subscriptions:
 * a new subscription has no history end date set (as expected)
 * if you renew it, a date is set.

This patch removes the setting of the history end date during renewal

Test plan:
 * create a subscription, go to subscription-detail.pl page, tab "Summary". No History end date is set
 * renew the subscription => a date has been set
 * apply the patch
 * create another subscription
 * renew it => no history end date has been set
 * sign-off

Signed-off-by: beroud <isabelle.beroud@univ-lyon3.fr>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>