[macOS] Fail builds on errors during the image generation (#1756)

* set -e and fix all the scripts

* add source utils to finalize_vm script

* change xcode version in postbuild script

* fix for softwareupdates and for xcode version

images/macos/provision/configuration/finalize-vm.sh

@@ -1,12 +1,16 @@
-#!/bin/bash
+#!/bin/bash -e -o pipefail
+
+source ~/utils/utils.sh
 
 # Close all finder windows because they can interfere with UI tests
 osascript -e 'tell application "Finder" to close windows'
 
-# Ignore available updates to prevent system pop-ups
-updateName=$(softwareupdate -l | grep "Title: " | awk -F[:,] '{print $2}' | awk '{$1=$1};1')
-if [ ! -z "$updateName" ]; then
-    sudo softwareupdate --ignore "$updateName"
+if is_Less_BigSur; then
+    # Ignore available updates to prevent system pop-ups
+    updateName=$(softwareupdate -l | grep "Title: " | awk -F[:,] '{print $2}' | awk '{$1=$1};1') || true
+    if [ ! -z "$updateName" ]; then
+        sudo softwareupdate --ignore "$updateName"
+    fi
 fi
 
 # Put documentation to $HOME root