don't let query_cache_size control query_cache_type

In 10.1 it was decided that changing the query_cache_size variable from its default value would enable query cache automatically by turning query_cache_type to ON even if it's set to OFF explicitly in confifguration.

This does not make much sense and is conter-intuitive.

Please, either remove this relation (so that one needs to effectively turn query_cache_type to ON to enable query cache), or remove the query_cache_type variable entirely.

This for the sake of coherence (one variable should not control another).

Thanks,
Rick