revid-cli: excessive logging of "revid:ring buffer read timeout" warning

[Alan Noble]

This message accounts for 98% of log messages (8108 of 8250 lines and counting), and caused the log file to grow to 1.5MB in less than 15 minutes.

Either the occurrence of this message should be truncated after repeating N times, or it should be a Debug message.

[Saxon Milton]

This is now a debug message