Revert use of set -u for bash

don't raise error due to variables
otherwise colcon setup.sh chokes from using an unbounded path variable

Author: ruffsl

.devcontainer/on-create-command.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-set -euxo pipefail
+set -exo pipefail
 
 export OVERLAY_MIXINS="release ccache lld"
 export CCACHE_DIR="$OVERLAY_WS/.ccache"

.devcontainer/update-content-command.sh

@@ -1,3 +1,3 @@
 #!/bin/bash
 
-set -euxo pipefail
+set -exo pipefail