cdc: do not create cdc$deleted columns for pks and cks
cdc: do not create cdc$deleted columns for pks and cks

Primary key and clustering key column should not have a corresponding
"cdc$deleted_<name>" column in cdc log table, because it does not make
sense to delete such a column from a row.

Fixes: #6049
Tests: unit(dev)

avikivity/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla