[master] Backport __init__.py changes to avoid conflicts with devel
Similar to https://github.com/DIRACGrid/DIRAC/pull/4894
BEGINRELEASENOTES
*Core CHANGE: New init.py layout to minimise conflicts with devel
ENDRELEASENOTES
Similar to https://github.com/DIRACGrid/DIRAC/pull/4894
BEGINRELEASENOTES
*Core CHANGE: New init.py layout to minimise conflicts with devel
ENDRELEASENOTES