Always calculate Escalator max row count the same way (#8740)

Always calculate Escalator max row count the same way (#8740)

* Rename getMaxEscalatorRowCapacity to describe what it does

* Always calculate Escalator max row count the same way

This changes Escalator to not take a horizontal scrollbar
into account when trying to determine "maximum visible rows". This will
add another row, compared to previous versions, when there is a horizontal
scrollbar. In reality, it would likely make sense to always add 10 more rows
to have some buffer above and below the visible area.

Fixes #8661