Key-value operations do not have a parent_span option

Recent changes made to the cxx client removed the parent_span option from certain operations when using new paths provided for accessing operations. In order to incorporate legacy durability, the wrappers have to use the new API paths and so do not have a way to pass in a parent_span to the operation. I think it might only impact mutation operations at the moment, but it is possible moving forward all KV operations are impacted.

See changes in these commits: 384839 & 4988db