test: fix unreliable assumption in js-native-api/test_cannot_run_js

Previously the test assumes that when the queued finalizer is run, it must be run at a point where env->can_call_into_js() is false (typically, during Environment shutdown), which is not certain. If GC kicks in early and the second pass finalizer is queued before the event loop runs the check callbacks, the finalizer would then be called in check callbacks (via native immediates), where the finalizer can still call into JS. Essentially, addons can't make assumptions about where the queued finalizer would be called. This patch updates the assertions in the test to account for that.