Do some sanity checking on license keys

[chynesNR]

We had a customer issue recently where they had set their NR license key in multiple places, and some of them weren't valid (one was set to a blank string). This resulted in inconsistent behavior and confusing agent logs. The only validation we currently do is to check if the key is still set to REPLACE_WITH_LICENSE_KEY. At the very least we should log a warning if it doesn't look like a good key. If we want to be extra robust we could use some "best match" logic if we encounter multiple keys.

Estimates

S

[workato-integration]

https://new-relic.atlassian.net/browse/NR-317236