Revert "Hotfix to allow for modal to be scrolled"

[saurabh6790]

Reverts #5486

It's breaking child table

[spa49]

I think this is due to the the different ways the modal Backdrop is used in the two cases
1 Modal Dialog
2 Freeze

both use the Modal Backdrop as underlay to clarify the use level but are handeles quiet differently

if you open the Modal dialog e.g. for email a new level is opened and a new scrollbar is added that however is not scrollable due to the backdrop overlaying it

If you open the childtable´s freeze the backdrop is appended in the same dimension, however no second scrollbar is added since the freeze sticks to the main level ghence is scrollable with the main scroll bar
interestingly the modal backdrop in this case is absolute

I tried different things like adding new z-index, height adjustment, max hight, max width, nothing worked. since there is no dokumentation of the UI architecture this is more or less fishing in the dark
I tried my best but the structure seems inconsistent
I think for the sake of usability and functionality this should be fixed somehow since a scrollbar needs to be scrollable or simply disapper!

so why not letting the Modal dialog behave like a freeze box?

Im sorry guys but due to a lack of qualification in this case Im not touching this again until someone can give further information and clarify the ins and outs of the architecture

best