After migrate a Continuous Aggregate from the old format to the new
using `cagg_migrate` procedure we end up with the following problems:
* Refresh policy is not copied from the OLD to the NEW cagg;
* Compression setting is not copied from the OLD to the NEW cagg.
Fixed it by properly copying the refresh policy and setting the
`timescaledb.compress=true` flag to the new CAGG.
Fix#4710