WL#7836: Use new DD API for handling partitioned tables

WL#7630 defines API for working with table partition information.

The scope of this WL is to use new DD API provided by WL#7630 to
handle partitioned tables. In the end, .par files should be gone
and all operations on partitioned tables should involve only new DD.

In other words, this WL is a counterpart of WL#6390 for partitioned
tables.

NF1: No user visible changes.