Always copy normalized files after a regress run (#6254)
Always copy normalized files after a regress run (#6254)

Our python based tests didn't always copy the normalized files after the
regress run. I had the problem where running the following command would
result in non-normalized files in the expected directory after running
our PG upgrade tests locally:

```
cp src/test/regress/{results,expected}/upgrade_list_citus_objects.out
```

This PR fixes that by always running `copy_modified` even if the tests
fail. The same was already being done for our perl based tests at the
end of the `pg_regress_multi.pl` file.

citusdata/citus,citusdata/citus,citusdata/citus,citusdata/citus,citusdata/citus