evolve settings for CAPO and CAPM3 image selection

This MR enables CI testing of the evolution brought by in sylva-projects/sylva-core#1101 (closed)

Context:

• our CI has had for a while some crude code to automatically compute image_key based on settings under common/all-ci-deployments.yml `.internal
• this needs to be kept for tests on Sylva 1.1, 1.2 and 1.3 branches
• for main this needs to be replaced by the use of os_image_key, the feature introduced by sylva-projects/sylva-core#1101 (closed)

What this MR does:

• for Sylva release 1.3 and before, nothing is changed
  • the removal of 1.2/node-os-suse.yml is only a cleanup (it contained data already present in common/node-os-suse.yml)
  • the image_key that was set in common is now only set in 1.1, 1.2 and 1.3
• to test sylva main, CI settings are changed under current to use os_image_selector instead of image_key
• in common, the way we select the OS image for test using suse OS now covers both the input for image_key computation and the input for os_image_selector

Note that the legacy way of automatically computing image_key is still necessary to keep under current because, until sylva-projects/sylva-core#2013 (closed) and sylva-projects/sylva-core#2014 (closed) land, we need this computation to enable images under sylva_diskimagebuilder_images.

💡 this MR is tested via sylva-projects/sylva-core!3702 (merged)