SERVER-14080 Have migration result reported in the changelog correctly

Signed-off-by: Benety Goh <benety@mongodb.com>
(cherry picked from commit d68aacd27b7abb5981d312e858bf5c5cc3b971b2)

Conflicts:
	src/mongo/s/d_migrate.cpp
SERVER-15629 Clear owned lines/polys correctly

Manual backport of commit:
27147aaf26aef235f8a65223e876adeea016886a
Merge remote-tracking branch 'upstream/v2.6' into v2.6