Add missing dep.

libsnapshot_nobinder uses update_metadata-protos. This
used to be optimized out, but now that SnapshotManager is
virtual, CreateUpdateSnapshots can no longer be optimized
out.

Bug: 148956645
Test: compiles
Change-Id: Iab1c9d92de2e558c73cf7da736c543b2ac8c0aa5