Fix role and collection dependency

With merge of [1] Depends-On for roles and services got broken as'
ZUUL_SRC_PATH is not really defined in the role, but lookup returnes
an empty string instead of falling back to the default value.

Also default value was pointing to the wrong directory anyway,
and not to /home/zuul.

Adjustments here should be fixing the behaviour.

[1] https://review.opendev.org/c/openstack/openstack-ansible/+/939151/27

Change-Id: I5eeb808b8eb2c21ef2e3ca898e872098152d0f1f

zuul.d/playbooks/pre-osa-requirements.yml

@@ -16,7 +16,8 @@
 - name: Prepare the OSA collection/role requirements
   hosts: "{{ pre_osa_host | default('all[0]') }}"
   vars:
-    _zuul_src_path: "{{ lookup('env', 'ZUUL_SRC_PATH') | default(lookup('env', 'HOME') ~ '/src') }}"
+    _zuul_src_path_env: "{{ lookup('env', 'ZUUL_SRC_PATH', default='') }}"
+    _zuul_src_path: "{{ (_zuul_src_path_env | length > 0) | ternary(_zuul_src_path_env, ansible_user_dir | default(lookup('env', 'HOME')) ~ '/src') }}"
   tasks:
     - name: Loading osa-gate-scenario vars
       ansible.builtin.include_vars: