MB-33900: Correct allocator context for ExecutorPool::shutdown
MB-33900: Correct allocator context for ExecutorPool::shutdown

Use the NonBucketAllocationGuard in ExecutorPool::shutdown to
match the allocation in ::get()

Change-Id: Ica550695d43c5c3b5d11f7b78c81404985ca967b
Reviewed-on: http://review.couchbase.org/108145
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>

daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine