Never remove the ansible_inventory if --dry-run is used

We currently do this:
if [ "$OPT_RETAIN_INVENTORY_FILE" = 0 ]; then
     # Clear out inventory file to avoid tripping over data
     # from a previous invocation
     rm -f $ANSIBLE_INVENTORY

This is very unexpected for a first-time user that has already deployed
a system and would like to inspect the tasks.

Let's remove it when we do not use the --dry-run option

Closes-Bug: #1775024

Change-Id: Ic52436ae2d5983e15f4e128edf1562510c3f7259

quickstart.sh

@@ -493,7 +493,7 @@ export ARA_DATABASE="sqlite:///${OPT_WORKDIR}/ara.sqlite"
 #set the ansible ssh.config options if not already set.
 source $OOOQ_DIR/ansible_ssh_env.sh
 
-if [ "$OPT_RETAIN_INVENTORY_FILE" = 0 ]; then
+if [ "$OPT_RETAIN_INVENTORY_FILE" = 0 && -z "$OPT_LIST_TASKS_ONLY" ]; then
     # Clear out inventory file to avoid tripping over data
     # from a previous invocation
     rm -f $ANSIBLE_INVENTORY