tests(busted): make all setup() and teardown() calls lazy

This turns on the `--lazy` flag for busted, which has the effect of
making all `setup()` and `teardown()` invocations behave as
`lazy_setup()` and `lazy_teardown()`.

.busted

@@ -1,5 +1,7 @@
 return {
   default = {
-    lpath = "./?.lua;./?/init.lua;"
+    lpath = "./?.lua;./?/init.lua;",
+    -- make setup() and teardown() behave like their lazy_ variants
+    lazy = true,
   }
 }