Agent "unknown" requires selection

[sharpphyl]

When entering or updating records with the agent "unknown," it is necessary now to select "unknown" from a list of 6 agents. We discovered that you can ignore the list, close the pop-up, and "unknown" will default into the field, but it will be red. In the bulkloader, it is correctly "unknown."

Previously, "unknown" was the default without any pop-up appearing and the field would turn green.

Screenshots

Desired outcome: make "unknown" the default without having to select it from the pop-up or close the pop-up.

Priority: normal. We have a work-around but it was much smoother in the past when it was the automatic default. Also, we don't want to encourage data-entry volunteers to ignore a red field.

[dustymc]

I am merging this with #7434 so that we can discuss the behavior of that form in one place.