removing explicit connection strings to int8r

This MR removes explicit connection strings to int8r, which I unfortunately put some time ago without paying attention. The pw for the writer users are visible, but the DB instance is int8r (test area, not production).

There are other connection strings currently in the history, see https://gitlab.cern.ch/search?group_id=4114&page=2&project_id=53790&repository_ref=&scope=blobs&search=password%3D&snippets=false but those involve read-only users as far as I can tell.