narrow the freshness window to 24h

in order to support removing non-integrated jobs from the gate we
need to reduce our freshness window to 24h as a good safety valve.

allow 72 hours for automatic rechecks, but once an approval vote
has happened, narrow that to 24 hours.

Change-Id: I13f8bc9d4adbe80ac555e7eb80efebadf1a30a45

modules/openstack_project/files/zuul/layout.yaml

@@ -16,7 +16,12 @@ pipelines:
         - event: comment-added
           require-approval:
             - username: jenkins
-              older-than: 48h
+              older-than: 72h
+        - event: comment-added
+          require-approval:
+            - approved: 1
+            - username: jenkins
+              older-than: 24h
     start:
       gerrit:
         verified: 0
@@ -38,7 +43,7 @@ pipelines:
           require-approval:
             - verified: 1
               username: jenkins
-              newer-than: 48h
+              newer-than: 24h
           approval:
             - approved: 1
         - event: comment-added
@@ -50,7 +55,7 @@ pipelines:
           require-approval:
             - verified: 1
               username: jenkins
-              newer-than: 48h
+              newer-than: 24h
     start:
       gerrit:
         verified: 0