Drop explicit dependency on Findbugs annotations

odlparent provides jsr305, and will eventually provide annotations
instead; so the dependencies no longer need to be explicitly added to
downstream projects.

Bug: 7663
Change-Id: If8fa8b231f9cb3d4a5e4fbdbd1b58e720756f5c0
Signed-off-by: Stephen Kitt <skitt@redhat.com>