MB-25010: Increase the max value size the Defragmenter considers
MB-25010: Increase the max value size the Defragmenter considers

Currently, the defragmenter does not consider values bigger than 3584B.
This used to be the largest allocation jemalloc would manage with
regions, but this has since increased to 14336B.

This patch bumps the max to 14336B, but will be followed up by an
improvement to get the max out of jemalloc to avoid this happening again
if we update jemalloc.

Change-Id: I60988908000c300530e815de406db9d817b7e550
Reviewed-on: http://review.couchbase.org/79948
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