Cleanup unused meetings to unblock gate

Remove unused Freezer meeting slot (unsused since April 2020) and
User committee meeting slot (unused since the merge with the TC) in
order to unblock the gate that was wedged when the channels those
meetings happen in were removed.

Change-Id: Iae3acc253815f4a48e4896e11f8f819c4b0b7075

meetings/freezer-meeting.yaml

@@ -1,14 +0,0 @@
-project:  Freezer Meeting
-meeting_id: freezer
-agenda_url: https://etherpad.openstack.org/p/freezer_meetings
-schedule:
-  - time:       '0900'
-    day:        Tuesday
-    irc:        openstack-freezer
-    frequency:  biweekly-odd
-    start_date: 20181009
-chair: Changcai Geng (gengchc)
-description:  >
-  The Freezer project team holds a biweekly team meeting on IRC.
-  The blueprints that are used as a basis for the Freezer project can be
-  found at https://storyboard.openstack.org/#!/project_group/freezer

meetings/user-committee-meeting.yaml

@@ -1,15 +0,0 @@
-project:  User Committee Meeting
-meeting_id: uc
-agenda_url: https://wiki.openstack.org/wiki/Governance/Foundation/UserCommittee
-schedule:
-  - time:       '1330'
-    day:        Thursday
-    irc:        openstack-uc
-    frequency:  weekly
-    start_date: 20171030
-chair:   Jaesuk Ahn (jayahn), Mohamed Elsakhawy (melsakhawy)
-description:  >
-  This is the weekly User Committee team meeting for multiple regions.
-  The User Committee's role is to represent the needs of the diverse range of OpenStack users and operators.
-  The User Committee mission includes consolidating user requirements, providing user feedback to dev teams, tracking OpenStack usage and deployment,
-  and working with the user groups worldwide to keep the OpenStack community vibrant and informed.