logging.googleapis.com is no longer valid, so stackdriver output plugin is using incorrect information

[esmerel]

I opened an issue for the docs here: fluent/fluent-bit-docs#2404 and then realized it should be in the code.

logging.googleapis.com has moved to docs.cloud.google.com/logging/docs/apis

I checked, and the stackdriver output plugin (at least) is using incorrect information in the code. The URLs should be updated to whatever the new URLs should be, and then the docs should be updated to match.