Iteration and stream operations with passivation disabled shouldn't use in memory

When passivation is disabled all entries are assumed to be in the cache loader/store. We currently try to merge these together in a sloppy way [1]. This first reads in memory and then from the store and keeps all keys from in memory to exclude them from the store. Unfortunately the store still has to pull the entries even for the already read keys, but just ignores them. This leads to a lot of inefficiency and memory bloat. Instead we should just return the store entries as is when passivation is disabled.

[1] https://github.com/infinispan/infinispan/blob/master/core/src/main/java/org/infinispan/interceptors/impl/CacheLoaderInterceptor.java#L506