Toolkit: set clearPropertiesOnDestroy to false by default

Toolkit: set clearPropertiesOnDestroy to false by default

instead of the upstream default of 'async'

we do this since it creates some problems with our callbacks which can
happen during component destruction. The upstream reasoning does not
really makes sense for us normally, since we do not keep any references
around for most things, and thus the garbage collector can claim it.

note that this is only for components, Ext.Base sets it to 'true' by
default and we do not change this since we normally do not extend
from non-components

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>