v2.5.1: Update to version 2.5.1 for official release

See RELEASE-NOTES.md for latest update details.

Change-Id: I2ca8dffe5b12144c841801b07fde16fdce15c2d9
(cherry picked from commit 2ab2df509d3d155c6c3bec317fbc8eaf7b3d6fed)