Remove the entity type from entity reference settings, if an entity has already been selected

Problem/Motivation

During the usability study, some participants found the entity reference settings confusing. When they chose to add a content/image/file/term/user reference field the system would present them with another dropdown asking them which entity they would like to reference, even though they just selected the entity.

After choosing a term reference, you have to choose a term reference again.

Some users though this was a different setting they had to fill in.

Proposed resolution

If a user has just selected the entity, hide the select box to select the entity.

Remaining tasks

Patch

User interface changes

A change to the entity reference settings form

API changes

None

Data model changes

None