make the shell script correct in cirros profile

The ">" should be replaced by "|" in the user_data section. Otherwise
the lines in this section would joined together into one line.

Change-Id: Id4f29d2c7ab4a40e12efbba1cfe02ece9be6d4af
Signed-off-by: Alex Yang <yangyang1@zte.com.cn>

examples/profiles/nova_server/cirros_basic.yaml

@@ -9,6 +9,6 @@ properties:
    - network: private
   metadata:
     test_key: test_value
-  user_data: >
+  user_data: |
     #!/bin/sh
     echo 'hello, world' > /tmp/test_file