Fix rocs1fileformattest: consider all default edge types "known"

All the default (well, both of them) edge types should be considered
"known" when loading a file, to prevent duplicating one of them.

This fixes the test, but leaves a different problem in place:
 - Older files of this filetype, created with a previous Rocs release,
   may have a corresponding ID which **isn't** the new bidirectional
   default edge type, and those will be loaded wrongly.
1 job for !8 with fix-tests in 13 minutes and 19 seconds (queued for 8 minutes and 29 seconds)
detached
Status Job ID Name Coverage
  Build
passed #14072
linux kf5-qt5 qt5.12

00:13:19

48.0%