Adapt more flags to Terraform 0.15

deps/rabbitmq_ct_helpers/src/rabbit_ct_vm_helpers.erl

@@ -516,7 +516,7 @@ destroy_terraform_vms(Config) ->
            Terraform,
            {"-chdir=~s", [TfConfigDir]},
            "destroy",
-           "-force",
+           "-auto-approve=true",
            {"-state=~s", [TfState]}
           ] ++ TfVarFlags,
     rabbit_ct_helpers:exec(Cmd, [{env, Env}]),

deps/rabbitmq_ct_helpers/tools/terraform/autoscaling-group/setup-vms.sh

@@ -132,7 +132,7 @@ start_vms() {
 
 destroy_vms() {
   terraform -chdir "$terraform_dir" destroy \
-    -force \
+    -auto-approve=true \
     -var="erlang_version=$erlang_branch" \
     -var="elixir_version=$elixir_version" \
     -var="erlang_cookie=$erlang_cookie" \