[8.0] feat (IAM): backport populate diracx section

[chaen]

This is to ease the migration to v9

BEGINRELEASENOTES
*Configuration
NEW: backport the export of the Sub in DiracX

ENDRELEASENOTES

[DIRACGridBot]

Sweep summary

Sweep ran in https://github.com/DIRACGrid/DIRAC/actions/runs/14084016029

Failed:

• integration
  cherry-pick 37e232f into integration failed
  check merge conflicts on a local copy of this repository

  git fetch upstream
  git checkout upstream/integration -b cherry-pick-2-37e232f6b-integration
  git cherry-pick -x -m 1 37e232f6b
  # Fix the conflicts
  git cherry-pick --continue
  git commit --amend -m 'sweep: #8093 feat (IAM): backport populate diracx section' --author='Christophe Haen <christophe.haen@cern.ch>'
  git push -u origin cherry-pick-2-37e232f6b-integration
  
  # If you have the GitHub CLI installed the PR can be made with
  gh pr create \
       --label 'sweep:from rel-v8r0' \
       --base integration \
       --repo DIRACGrid/DIRAC \
       --title '[sweep:integration] feat (IAM): backport populate diracx section' \
       --body 'Sweep #8093 `feat (IAM): backport populate diracx section` to `integration`.
  
  Adding original author @chaen as watcher.
  
  BEGINRELEASENOTES
  *Configuration
  NEW: backport the export of the Sub in DiracX
  
  ENDRELEASENOTES
  Closes #8101'