Change wording in the log output

[Luci2015]

Is your feature request related to a problem? Please describe.
This line in the log "umapi_client.auth - auth token is missing or expired - refreshing now" is a support case generator. We've been asked a lot about it, and, although we can explain it, it's better if it did not raise questions in the first place

Describe the solution you'd like
Please rephrase this log line so that it just says something like "obtaining an access token" or similar.

[adorton-adobe]

What if we just made it debug level and not info? Would that suffice?

[Luci2015]

even with debug mode, Customers see the message when we deploy them to UST or assist them update from JWT to OAuth, and ask about it (we always use debug in these cases). Can you just remove the "auth token is missing or expired" part?