Bug 1857836 - Temporarily add expiry policy for "try". rs=bustage-fix DONTBUILD

Until D190482 is on mozilla-central.

--HG--
extra : histedit_source : 893a1e9f5429401c8187899e62362ab97a3d00ac

taskcluster/ci/config.yml

@@ -392,6 +392,12 @@ mac-signing:
 
 expiration-policy:
     by-project:
+        try:
+            default: 28 days
+            shortest: 7 days
+            short: 14 days
+            medium: 28 days
+            long: 28 days
         try-comm-central:
             default: 1 month
             shortest: 7 days