write gerrit openstack/2.8 branch activity to #openstack-infra channel

We have forked gerrit 2.8 and are actively adding small patches to it therefore
change activity should be sent to #openstack-infra channel.

Change-Id: I0a237fb8d79e374750a9dd0b59995b8dd663d926
Merge "write gerrit openstack/2.8 branch activity to #openstack-infra channel"