EnabledModuleCachingPluginAccessor cache shouldn't expire

The EnabledModuleCachingPluginAccessor cache has a 30 minute expiry. We've observed a scenario in CAC where a bunch of items will expire at the same time, and then subsequently all request threads block waiting for these items to be recomputed.

Remove the cache expiry, or implement the Guava refresh() method to asynchronously recompute this stuff in the background.