Remove docs for structured APT content

With Katello nightly, all Deb content will be in structured APT mode
only.

Depends on PR 11487 in katello

Author: maximiliankolb

guides/common/assembly_importing-content.adoc

@@ -27,10 +27,6 @@ endif::[]
 ifndef::satellite[]
 include::modules/proc_extracting-gpg-public-key-fingerprints-from-release-files.adoc[leveloffset=+1]
 
-include::modules/con_structured-apt-content.adoc[leveloffset=+1]
-
-include::modules/proc_enabling-structured-apt-content.adoc[leveloffset=+1]
-
 include::modules/proc_adding-custom-deb-repositories.adoc[leveloffset=+1]
 
 include::modules/proc_synchronizing-ubuntu-expanded-security-maintenance-content.adoc[leveloffset=+1]