[Enhancement] Make usePopover default behavior in dropdown

[RasmusKjeldgaard]

• I have written a good issue

Describe the enhancement

There are some reports about dropdown not correctly placing itself on top of content , e.g. #3691 and others raised in our support channels. These have proven to be solved by usePopover="true", so we should make it the default. It is battle-tested, and known issues have been solved as per #2087.

Solving this issue will also solve above mentioned issue (#2087).

Also, consumers have to explicitly set usePopover for dropdown in calendar, which is not ideal, and would also be solved by this.

Describe the solution you'd like

Make usePopover true by default and deprecate the input all together, by warning when it is set. Remove the input all together in the next major.

Are there any additional context?

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