(bug 47315) Add $wmfThrottlingExceptions for it.wiki GLAM event

Increasing account creation limits for it.wikipedia GLAM event
on April 20, 11:00-18:00 UTC per request.

Bug: 47315
Change-Id: I84153feb5a9e5af0a80a31d0f8e69b27437c8970
Merge "(bug 47315) Add $wmfThrottlingExceptions for it.wiki GLAM event"