Bug 27683: Bind results of GetAnalyticsCount to the EasyAnalyticalRecords pref

Bug 27683: Bind results of GetAnalyticsCount to the EasyAnalyticalRecords pref

C4::Items::GetAnalyticsCount is part of the easy analytics feature.
Like Bug 20702 make early return when the system preference EasyAnalyticalRecords is disabled.
Actually it may block an item deletion for wrong reason.

Test plan :
1) Dont apply patch
2) Build an item and a linked analytical record with 773$0 and $9
3) Enable EasyAnalyticalRecords
4) Try to delete the item
5) You have an alert because linked to analytics
6) Disable EasyAnalyticalRecords
7) Try to delete the item
8) You have an alert because linked to analytics
9) Apply patch
10) Try to delete the item
11) No alert, it works :D

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>