TT#33375 Switch asterisk -rx "odbc show" -> "odbc read ODBC_VMGREETUNAVAIL test exec"

The output of 'asterisk -rx "odbc show"' is not a 'current' state while the
cached one, also it reports unreliable data depending on which service is
starting first asterisk or db. See the ticket for the samples here.

Change-Id: I8bbdaba077c92369d6c61711a3d6382474cd2dcb
(cherry picked from commit 5005c9b3d1)
(cherry picked from commit fa975d1ddf)

templates/920_service-asterisk-odbc-pro.yaml.tt2

@@ -17,10 +17,10 @@
 command:
 
 [% IF is_proxy && asterisk.enabled == "yes" && node_state == 'active' -%]
-  asterisk -rx "odbc show":
+  asterisk -rx "odbc read ODBC_VMGREETUNAVAIL test exec":
     exit-status: 0
     stdout:
-    - "/Number of active connections: 1/"
+    - "/Returned 1 row/"
     stderr: []
     timeout: 10000