raise TTL for gerrit.wikimedia.org from 60s to 1H

Gerrit has been migrated to a new IP in September. 480a88c2 changed the
TTL to 60 seconds to prepare the migration done on Sep 4th by fb7e27b5.

This simply reset the TTL back to 1H.

The reason is that some people, including me, had DNS resolution failure
from time to time. I suspect it might be due to the low TTL.
Regardless, 1H is enough now.

Change-Id: I68c1321c75eee0320e4f8a3866d7367f06cc9846