Consider to not warn about deprecated properties in logs when the value is not deprecated

When there is an initialisation of database descriptor for tools, for example via "Util.initDatabaseDescriptor()", it will eventually buble up to "YamlConfigurationLoader.check" where this is logged:

if (!deprecationWarnings.isEmpty())
logger.warn("{} parameters have been deprecated. They have new names and/or value format; For more information, please refer to NEWS.txt", deprecationWarnings);

For example, I saw this log:

WARN  09:07:42,486 [key_cache_save_period, counter_cache_save_period, row_cache_save_period] parameters have been deprecated. They have new names and/or value format; For more information, please refer to NEWS.txt

The "problems" I see are two:
1) it pollutes the console for tool commands, when a tool needs to initialise DD, at the very beginning of the output.
2) When you look closely, for example at key_cache_save_period, by default, in cassandra.yaml, it has value "4h". My question is: why is it necessary to mark that as deprecated when the value is already in new format? In other words, I would log that warning only in case that the expected value of a property is not in the new format. But when it already is, why do we need to inform a user about that?

I think it would require to take some extra care for cases like these in YamlConfigurationLoader.getProperty to not add deprecated properties if their value is already new.