Fix shellcheck warnings in shell scripts

- Fix SC2125: Quote GOPRIVATE/GONOSUMDB values in ci_setup.sh
- Fix SC1091: Add source=/dev/null for dynamically sourced lib_luxd_clone.sh
- Fix unbound variable errors in shellcheck.sh for arrays and args
- Add -x flag to shellcheck for following sourced files

scripts/build_antithesis_images.sh

@@ -15,6 +15,7 @@ EVM_PATH=$( cd "$( dirname "${BASH_SOURCE[0]}" )"; cd .. && pwd )
 # TODO(marun) Support use of a released node image if using a release version of luxd
 
 source "${EVM_PATH}"/scripts/constants.sh
+# shellcheck source=/dev/null
 source "${EVM_PATH}"/scripts/lib_luxd_clone.sh
 
 clone_luxd "${LUX_VERSION}"

scripts/build_docker_image.sh

@@ -92,6 +92,7 @@ if ! docker pull "${LUXD_NODE_IMAGE}"; then
   LUXD_NODE_IMAGE="${LUXD_LOCAL_IMAGE_NAME}:${LUX_VERSION}"
   echo "Building ${LUXD_NODE_IMAGE} locally"
 
+  # shellcheck source=/dev/null
   source "${EVM_PATH}"/scripts/lib_luxd_clone.sh
   clone_luxd "${LUX_VERSION}"
   SKIP_BUILD_RACE=1 \

scripts/shellcheck.sh

@@ -46,10 +46,14 @@ fi
 
 IGNORED_CONDITIONS=()
 for file in ${IGNORED_FILES}; do
-  if [[ -n "${IGNORED_CONDITIONS-}" ]]; then
+  if [[ ${#IGNORED_CONDITIONS[@]} -gt 0 ]]; then
     IGNORED_CONDITIONS+=(-o)
   fi
   IGNORED_CONDITIONS+=(-path "${REPO_ROOT}/${file}" -prune)
 done
 
-find "${REPO_ROOT}" \( "${IGNORED_CONDITIONS[@]}" \) -o -type f -name "*.sh" -print0 | xargs -0 "${SHELLCHECK}" "${@}"
+if [[ ${#IGNORED_CONDITIONS[@]} -gt 0 ]]; then
+  find "${REPO_ROOT}" \( "${IGNORED_CONDITIONS[@]}" \) -o -type f -name "*.sh" -print0 | xargs -0 "${SHELLCHECK}" -x "${@:+$@}"
+else
+  find "${REPO_ROOT}" -type f -name "*.sh" -print0 | xargs -0 "${SHELLCHECK}" -x "${@:+$@}"
+fi