Fixed log of vault data return when retrieving to a file.

When retrieving data from a vault using `out` to store the data in a
file resulted is random characters being returned and logged. These
characters could generate a traceback print from Ansible's logger,
without breaking the script.

The reason for that is that the result from `vault_retrive` was being
processed when it was not needed, and data was beeing returned, when
it shouldn't.

This patch fixes this behavior by supressing the return data when `data`
is not available, and only raising an error if it should be available.

tests/vault/test_vault_symmetric.yml

@@ -53,7 +53,7 @@
       out: "{{ ansible_env.HOME }}/data.txt"
       state: retrieved
     register: result
-    failed_when: result.changed
+    failed_when: result.changed or result.failed or (result.vault.data | default(false))
 
   - name: Verify retrieved data.
     slurp: