AttachmentsClassLoader updates needed to enable ENT-6152 backport
fixes memory leak and file handle leak issues. This fix is being backported to ENT 4.4. ENT 4.4 relies on OS core, so also need to backport from OS 4.6 to OS 4.4 some AttachmentClassLoader updates.
These are updates related to cache size and switching the cache to a caffeine based one.