Should demote log-level for `directory_water - No path found ...` (for library usage)?

[EricCousineau-TRI]

The downstream issue is: wandb/wandb#3274

I'm not sure how useful this information in the context of downstream use case (wandb + inspecting event logs).

Is it possible to demote this to debug? If not, is there a way to only promote this if running the tensorboard binary?
https://github.com/tensorflow/tensorboard/blob/2.8.0/tensorboard/backend/event_processing/directory_watcher.py#L122-L125

[bileschi]

Commented on PR #5578