Fix runtime install aborting before it builds anything

build_workspace() sources /opt/ros/jazzy/setup.bash, which dereferences
AMENT_TRACE_SETUP_FILES while the script runs under `set -euo pipefail`.
Under `set -u` that is an unbound-variable error, so the installer exited
before rosdep/colcon ever ran:

  /opt/ros/jazzy/setup.bash: line 8: AMENT_TRACE_SETUP_FILES: unbound variable

Relax `set -u` around the source only. Verified in the jazzy-dev image:
build_workspace now reaches rosdep + colcon.

Bug found by Jayadev Rana by running the scaffold end to end; the original
PR was verified with `bash -n`, which does not execute build_workspace.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: kaiaai

ubuntu/install_oomwoo_runtime_jazzy.sh

@@ -135,7 +135,11 @@ prepare_workspace() {
 }
 
 build_workspace() {
+  # ROS 2's setup.bash dereferences unset variables (AMENT_TRACE_SETUP_FILES),
+  # which aborts the script under the `set -u` above. Relax it for the source.
+  set +u
   . /opt/ros/jazzy/setup.bash
+  set -u
   cd "$WORKSPACE"
   rosdep install --from-paths src --ignore-src -y
   colcon build --symlink-install