No way to reset Footnote text input after removing original value

3.6.3/public//nesttest/UAT_2020_12_05/osprey/

`Adverse Events` -> `Common AE Plot`

At the bottom, there are 2 text input fields, `Title` and `Footnote`. `Title` will retain the original value as a dropdown suggestion if the user removed it. `Footnote` does not have this feature. No reason it shouldn't be added.

In the `Adverse Events` -> `AE Overview Plot`

Both the `Title` and `Footnote` are missing this feature.

Provenance:
```
Creator: junlue
```

Locate the input definitions for the Common AE Plot and AE Overview Plot, then compare how the Title field preserves removed values as dropdown suggestions. Check how the Footnote fields are configured in both plots; done means removed Footnote values are suggested again, and the same behavior exists for both Title and Footnote in AE Overview Plot.

Written by the indexing model from the issue text.