Adapt ImportReplicationChanges to current DBD::Pg

This is mostly the same as pull request #1425, just for replication/ImportReplicationChanges instead of MBImport.pl (I grepped this time to make sure there aren’t even more problematic uses of COPY). Unlike MBImport.pl, this script also used outdated methods for sending data, which still work but are “heavily deprecated” according to the documentation, so I updated those, too.

I couldn’t really test this. @mayhemchaos has confirmed that swapping the lines fixed the issue for him, though, and MBImport.pl has been using the new API for years, so I’m confident it will work. :)