namespace:  Increase mount point TTLs to reduce test flakiness.

Change-Id: I8a3d1da48838ac8aae1123a89fe28cc86b20ad21
diff --git a/runtime/internal/naming/namespace/all_test.go b/runtime/internal/naming/namespace/all_test.go
index 638577a..fd269d5 100644
--- a/runtime/internal/naming/namespace/all_test.go
+++ b/runtime/internal/naming/namespace/all_test.go
@@ -235,7 +235,7 @@
 	j2MP  = "joke2"
 	j3MP  = "joke3"
 
-	ttl = 100 * time.Second
+	ttl = 5 * time.Minute
 )
 
 // runMountTables creates a root mountable with some mount tables mounted