Disable ceilometer's swift middleware

This middleware is spamming rsyslog with rabbitmq debug logs, making
this middleware practically unusable in combination with rsyslog. Because of
this, the rsyslog logs now account for 35% percent of the logs we store
in logstash. Until the underlying problem is solved disable the
offending code.

Change-Id: I50a73ae6beb1a11c41225340779fe8d7a1081e46
Related-Bug: #1294789