Geant4AssemblyVolume: use the same copy ID for the Geant4 Volume as w…

[andresailer]

…as set in DD4hep geometry construction

BEGINRELEASENOTES

• Geant4AssemblyVolume: use the same copy ID for the Geant4 Volume as was set in DD4hep geometry construction, fixes Issue with Assembly volume and g4-copynumbers #1360 .

ENDRELEASENOTES

• Check if this affects checksums or GDML output?
  • I don't think it can affect checksums, because those are calculated on the DD4hep/TGeo geometry
  • I didn't see any difference in the GDML ordering or copynumber tag in SiD gdml test

[github-actions]

Test Results

   14 files     14 suites   5h 36m 4s ⏱️
  368 tests   368 ✅ 0 💤 0 ❌
2 531 runs  2 531 ✅ 0 💤 0 ❌

Results for commit 4447c02.