Enforce default column family options correctly

Summary:
There are several layers of column family options values. In order:

1) Defaults defined in ColumnFamilyOptions constructor
2) Defaults set explicitly in ha_rocksdb.cc code
3) Defaults set by rocksdb_default_cf_options sysvar
4) Per-CF options specified via rocksdb_cf_options_file

The settings from (2) were omitted inadvertently. This fixes it.