Owner email entry bug

Update for auto-complete feature: when entering owner on edit, browser tester should click on user that pops up, as it is no longer enough to enter email text and click save.  See [#59527138](https://www.pivotaltracker.com/story/show/59527138) for story on how to handle this user behavior.

First commit (2a76876) is a fix that makes the tester select the first autocomplete item.  This should normally grab the correct user.  However, because of a bug, many persons (whose emails don't match that which is input) are appearing.  The second commit (fc9f394) is a workaround for this, providing a selector that makes sure to click on an auto-complete item that matches the input email address.

Note: current ggrc-core has bug that prevents auto-complete click from actually filling in the field or selecting the matching person, and this is being fixed.