Large Scale SIG now meets monthly

Switch scheduling to monthly without rotation, following the discussion
at the March 6 meeting.

Also allow dots in IRC usernames so that Felix does not trigger the typo
police.

Change-Id: I0f88241560e887362f990dd2dc808732cdeca515

meetings/large-scale-sig-meeting.yaml

@@ -2,18 +2,13 @@ project:  Large Scale SIG Meeting
 meeting_id: large_scale_sig
 agenda_url: https://etherpad.openstack.org/p/large-scale-sig-meeting
 schedule:
-  - time:       '1600'
-    day:        Wednesday
-    irc:        openstack-operators
-    frequency:  quadweekly
-    start_date: 20231129
   - time:       '0900'
     day:        Wednesday
     irc:        openstack-operators
-    frequency:  quadweekly-alternate
+    frequency:  fourth-wednesday
-    start_date: 20240110
+    start_date: 20240327
 chair:  >
-  Thierry Carrez (ttx), Kristin Barrientos (kbarrientos)
+  Thierry Carrez (ttx), Arnaud Morin (amorin), Felix Huettner (felix.huettner)
 description:  >
   Facilitating the scaling journey of OpenStack operators since 2019! Please
   join the Large Scale SIG meeting if you are interested in helping OpenStack

tools/check_chair.py

@@ -33,7 +33,7 @@ def check_chair(chair):
     msg = ''
     for chair in chairs:
         chair = chair.rstrip().lstrip()
-        ok = bool(re.match(r"^[\w '.-]+\([\w\d_-]+\)$", chair))
+        ok = bool(re.match(r"^[\w '.-]+\([\w\d_\.-]+\)$", chair))
         all_good &= ok
         msg += "\t%s: %s\n" % (chair, BOOL_STR[ok])