Extra space at the end of `PopupView`

[CalebRas]

There appears to be extra space at the bottom of the PopupView which makes it difficult to place another view beneath the it.

[yo1995]

When dragging downward the floating panel, one can see that the 2 lists start to shift closer and eventually get rid of the empty space. I think this might be a limitation of the floating panel's auto layout.

[yo1995]

Similar to #551

[dfeinzimer]

Esri/arcgis-maps-sdk-swift-samples#661 changed the Floating Panel in this and other samples to sheets and popovers, making this no longer reproducible.

I believe the core of this issue is still captured accurately in open issue #551, noted by Ting above, so closing this as not planned, for now.