JobExpirationCheckInterval now defaults to 30 minutes

With the new ExpirationManager implementation, Hangfire now uses much
less queries to perform the cleanup, so we can decrease the expiration
checking interval.

src/Hangfire.SqlServer/SqlServerStorageOptions.cs

@@ -35,7 +35,7 @@ public SqlServerStorageOptions()
 #pragma warning disable 618
             InvisibilityTimeout = TimeSpan.FromMinutes(30);
 #pragma warning restore 618
-            JobExpirationCheckInterval = TimeSpan.FromHours(1);
+            JobExpirationCheckInterval = TimeSpan.FromMinutes(30);
             CountersAggregateInterval = TimeSpan.FromMinutes(5);
             PrepareSchemaIfNecessary = true;
             DashboardJobListLimit = 50000;