[zfs-2.2.3] Enable zfs_bclone_enabled on cp_files tests

cp_files_002_pos uses BRT, so enable block cloning in setup/cleanup.
This is only something we need to do in zfs-2.2.3, since 2.2.x ships
with block cloning disabled by default.

Signed-off-by: Tony Hutter <hutter2@llnl.gov>