[Ephemeral] Remove Warmup task from EphemeralBucket
[Ephemeral] Remove Warmup task from EphemeralBucket

Ephemeral buckets do not have warmup (there's no data ever persisted,
so we shouldn't attempt to load anything).

Forcefully disable warmup from the configuration for Ephemeral
buckets.

Change-Id: I6aa7ef779129a000ccf365aac36fa1a07861c006
Reviewed-on: http://review.couchbase.org/71384
Reviewed-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

daverigby/kv_engine,couchbase/ep-engine,couchbase/ep-engine,daverigby/ep-engine,membase/ep-engine,daverigby/kv_engine,membase/ep-engine,membase/ep-engine,couchbase/ep-engine,daverigby/ep-engine,daverigby/ep-engine,membase/ep-engine,daverigby/ep-engine,daverigby/kv_engine,daverigby/kv_engine,couchbase/ep-engine