Remove ngl_codegen from RELEASE_GROUP3_TARGETS

- ngl_codegen is a code generation tool only needed during development
- Not required for release scope builds (TetraIF, Z, Lts/Common subset)
- Fixes persistent 'No rule to make target ngl_codegen' error

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

qt6-after/qt6-migrated-legatus/new_docker_build.sh

@@ -577,7 +577,6 @@ RELEASE_GROUP3_TARGETS=(
   # Lts/Common library targets (for tests)
   LtsCoordTrans
   LtsLicence
-  ngl_codegen
   MockCoordTrans
   # Test executables for release scope modules
   # Note: nglcomp_test excluded - compression "Unknown error" in Qt6 (requires investigation)