sdk: Restore the image build

Commit 921c72f1 decoupled ospack building from image buiding, but a
typo caused the pipeline to only build the ospack for the SDK and not
the image.

Flip the flag so we build it again.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

Jenkinsfile

@@ -386,7 +386,7 @@ def artifacts = [:]
 ////////// Amd64 //////////
 artifacts["Sdk"] = buildImages("amd64", "sdk", [ "sdk" ],
                            "--scratchsize 10G",
-                           false, false, false, production)
+                           true, false, false, production)
 
 // Types for all boards, common debos arguments, sysroots and ostree
 def types = [