Add jacobhobbie@google.com to trust owners.

With cbrubaker and vishwath leaving Google soon, someone should own this. jacobhobbie has done the most active work with the trust code recently and seems appropriate

Change-Id: Icf3d411f9f4acfc7af28829efa061b02a997f6d4
(cherry picked from commit 71b6b8eb)
Bug: 280469670
Test: no test needed