[feat] Review logic to check for non-ephemeral stack

We want to cloud-importer to be idempotent, and due to the ephemeral - non-ephemeral orchestration in case of updates on the non-ephemeral part (i.e adding a new shared org) it will try to create the ephemeral stack.

We want to add a logic to check for existing non-ephemeral stack if that is the case avoid the ephemeral one and directly update what is needed.

Start by tracing the ephemeral/non-ephemeral orchestration path used when updating an existing import, since no files or tests are named. Identify where stack creation is triggered, then verify that an existing non-ephemeral stack is detected and updated directly without creating an ephemeral stack, preserving idempotent behavior.

Written by the indexing model from the issue text.