MULE-6831: Applications deleted when deployment fails

_ Cleaning test code
(cherry picked from commit 3800199)
MULE-6831: Applications deleted when deployment fails

_ Cleaning test code
(cherry picked from commit ef22b77)
MULE-6831: Applications deleted when deployment fails

_ Adding a system property to configure the interval used to check for updated apps in the MuleDeploymentService
(cherry picked from commit c9d26e3)