efl_gfx_arrangement: change content_padding param type and remove scalable

efl_gfx_arrangement: change content_padding param type and remove scalable

Summary:
This change `content_padding` parameter type to int from double for consistency
of size properties.

`scalable` should be handled in more common size API.

Co-authored-by: Mike Blumenkrantz <zmike@samsung.com>
ref T7864

Test Plan: ninja test

Reviewers: zmike

Reviewed By: zmike

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Maniphest Tasks: T7864

Differential Revision: https://phab.enlightenment.org/D10154