controller: Drop noisy log message about certificates

I often turn to the controller pod logs to debug issues, and
this log message is repeated very often. While it was
probably useful at the time the feature was being developed/tested
I doubt it will be necessary in the future.

In the end, the status really is the debugging frontend I believe.

controller: Drop noisy BaseOSContainerImage log message

In general we should avoid logging unless something changed.
I don't believe we need this log message, we can detect OS
changes from e.g. the MCD logs.