Option to disable the dnf update from the assemble script

The assemble script runs a dnf update by default during the ee build. It would be useful to have the default behavior to not run the update (for consistency, disconnected environments...etc), and instead have an argument to update if desired.

Note: Opening issue in this repo based on the recommendation in https://github.com/ansible/ansible-builder/issues/339

Start by reading the assemble script and trace where the dnf update runs during the EE build. Confirm the existing build invocation and determine how an opt-in update argument should be exposed. Done means updates are skipped by default, run when explicitly requested, and the build behavior is verified in both modes.

Written by the indexing model from the issue text.