Don't init/set all actions sets in WorkbenchWindow on startup, this
triggers code activation for invisible action sets. Instead, populate
all legacy actions sets into the model before opening Customize
Perspective Dialog.

Change-Id: Ida27af57f44d56fb52db92bfb3e0c0f23d81e3a3
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>