Free up unused Designate meeting slot

Designate team apparently has not been meeting on IRC since
9/2018. Let's clean up the agenda slot so that we don't
give out the impression that it actually does, and encourage
other ways to reach out to the team.

Change-Id: Ieaa967c5d1e70e6215527bf4ee3b2b496952382b

meetings/designate-dnsaas-meeting.yaml

@@ -1,19 +0,0 @@
-project:  Designate (DNSaaS) Meeting
-meeting_id: designate
-agenda_url: https://wiki.openstack.org/wiki/Meetings/Designate
-schedule:
-  - time:       '1100'
-    day:        Wednesday
-    irc:        openstack-meeting
-    frequency:  quadweekly
-    start_date: 20180606
-  - time:       '1700'
-    day:        Wednesday
-    irc:        openstack-meeting
-    frequency:  quadweekly-alternate
-    start_date: 20180606
-chair:  Graham Hayes (mugsie)
-description:  >
-  The DNSaaS team holds a bi weekly IRC meeting, alternating between UTC
-  mornings and evenings. Meeting logs are available at
-  http://eavesdrop.openstack.org/meetings/designate/