Allows switching off the plugins that are discovered on classpath.
When a particular plugin is switched off, the default Mockito behavior is used.
For example, if Android's dexmaker MockMaker is switched off,
Mockito default MockMaker implementation is used MockMaker
Mockito invokes this method for every plugin found in the classpath
(except from the PluginSwitch implementation itself).
If no custom plugins are discovered this method is not invoked.