Remove USE_SSL support

tls-proxy is the way we're now doing a standard install using https
between services. There is a lot more work to make services directly
handle https, and having python daemons do that directly is a bit of
an anti pattern. Nothing currently tests this in project-config from
my recent grepping, so in the interest of long term maintenance,
delete it all.

Change-Id: I910df4ceab6f24f3d9c484e0433c93b06f17d6e1
diff --git a/lib/tempest b/lib/tempest
index f6fc57d..04f8f6a 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -279,7 +279,7 @@
     fi
     iniset $TEMPEST_CONFIG identity auth_version ${TEMPEST_AUTH_VERSION:-v3}
 
-    if is_ssl_enabled_service "key" || is_service_enabled tls-proxy; then
+    if is_service_enabled tls-proxy; then
         iniset $TEMPEST_CONFIG identity ca_certificates_file $SSL_BUNDLE_FILE
     fi