CA-118781: revert init order changes

Unfortunately we have to revert the previous 7018eaa1 on strict
initialization order.

This is due to some spaghetti calling pattern in our code. In VDI class
and its children, we have the following calling stack:

   Child.__init__ -> Parent.__init__ -> Child.load

While Child.load is called, it assumes that some attributes have been
initialized, but at this point neither Child.__init__ and Parent.__init__
has completed yet (still on stack). This forced us to initialize some
Child class's attributes before calling Parent.__init__.

This is not pretty, but changing this pattern demands quite a lot of
changes. To unblock trunk integration, here we reverted the previous
changes and use some workaround instead.

Also indent the if-else clause demanded by Vineeth.

Signed-off-by: Zheng Li <zheng.li@eu.citrix.com>