rapid-cdn: Replace trafficserver_cache_availability promise

Replace trafficserver_cache_availability with check_command_execute which
has the same functionality.

The eventual message from trafficserver_cache_availability will be visible
anyway.

software/rapid-cdn/buildout.hash.cfg

@@ -22,7 +22,7 @@ md5sum = 5784bea3bd608913769ff9a8afcccb68
 
 [profile-frontend]
 filename = instance-frontend.cfg.in
-md5sum = 081aef1b071585e5f334a93d6d4969d0
+md5sum = 8b91d4ddba399794652d49917b82828d
 
 [profile-master]
 filename = instance-master.cfg.in

software/rapid-cdn/instance-frontend.cfg.in

@@ -639,9 +639,10 @@ environment = TS_ROOT=${buildout:directory}
 
 [trafficserver-promise-cache-availability]
 <= monitor-promise-base
-promise = trafficserver_cache_availability
+promise = check_command_execute
 name = trafficserver-cache-availability.py
-config-wrapper-path = ${trafficserver-ctl:wrapper-path}
+config-command = ${trafficserver-ctl:wrapper-path} metric get proxy.process.cache.percent_full
+report-anomaly = False
 
 [trafficserver-rotate-script]
 < = jinja2-template-base