StorageSinkConnectorConfig#avroDataConfig() uses wrong AvroDataConfig keys

[dcsobral]

When creating an AvroDataConfig out of the values present in StorageSinkConnectorConfig, the method avroDataConfig() uses StorageSinkConnectorConfig as keys in the map, and, thus, end up not passing the schema cache config size, whose keys differ between them -- schema.cache.size on storage, schemas.cache.config on avro data.