Deprecate eager near caching

In its current form, eager near caching can lead the server to run out of direct memory, see ISPN-5523. The reason that's happening is because we're having to send events containing keys + values for each put() operation, indiscriminately to clients. So, regardless of what the client stores in the near cache, the client receives key+value information for all keys, as each key is created/modified, and this is having a big toll on the capabilities of the server to push those events to clients.

So, we have decided to deprecate eager near caching in Infinispan 8.0, and we'll remove it completely for Infinispan 9.0.

Lazy near caching still remains and works well because events are smaller since no value is sent to clients. Lazy near caching is still indiscriminate but we have plans to make it more selective, so that for example, only modified/removed events are sent for those keys that are stored in the client near cache, which would reduce traffic considerably (new jira to be created).