Agent initialization was fixed

When Murano Agent is disabled Agent was not
initialized properly which caused deployment errors
even if no agent calls made

Change-Id: I047b512cafe71650d6a5c7edc7863f0231292a22
Closes-Bug: #1670511
Co-Authored-By: Stan Lagun <slagun@mirantis.com>

murano/engine/system/agent.py

@@ -45,10 +45,8 @@ class Agent(object):
         if CONF.engine.disable_murano_agent:
             LOG.debug('Use of murano-agent is disallowed '
                       'by the server configuration')
-            return
-
         self._host = host
-        self._enabled = True
+        self._enabled = not CONF.engine.disable_murano_agent
         env = host.find_owner('io.murano.Environment')
         self._queue = str('e%s-h%s' % (env.id, host.id)).lower()