TOKENINFO_URL is not set when the healthcheck of local planb fails

[shuhei]

A comment suggests that the global tokeninfo should be used when the local healthcheck fails. However, TOKENINFO_URL doesn't seem to be set to the global one when the healthcheck fails.

Does the comment suggest that applications should keep the global tokeninfo URL in them and use the local one only when TOKENINFO_URL is set? Or should the script fallback to tokeninfo_url if the healthcheck fails?

[shuhei]

Background: I had an incident that an instance started with an unhealthy local planb tokeninfo. The application was not using TOKENINFO_URL env variable, and the fallback to a global one didn't kick in. I am thinking of how to improve it.