Removes unnecessary mark_log() call that was throwing off the watch_log_for* functions

I think this was perhaps left out in your refactoring of this block in c553f62e3afc95323808e383a49dca09638aa0b4 - that is, I don't see the reason to add a (node,mark) twice.

This fix makes the repair_test dtest pass, whereas it's currently broken without it.