Remove unnecessary -2016 from copyrights

README.md

src/core/lib/iomgr/ev_poll_and_epoll_posix.c

src/core/lib/iomgr/ev_posix.c

src/core/lib/iomgr/ev_posix.h

src/csharp/grpc.native.csharp/grpc.native.csharp.nuspec

src/python/grpcio/grpc/beta/implementations.py

src/python/grpcio/tests/interop/_secure_interop_test.py

src/python/grpcio/tests/interop/client.py

src/python/grpcio/tests/unit/beta/_beta_features_test.py

src/python/grpcio/tests/unit/beta/_face_interface_test.py

test/core/end2end/fixtures/proxy.c

test/core/end2end/tests/idempotent_request.c

test/core/internal_api_canaries/iomgr.c

test/core/internal_api_canaries/support.c

test/core/internal_api_canaries/transport.c

test/core/surface/server_test.c

tools/gce/create_interop_worker.sh

tools/run_tests/performance/build_performance.sh

tools/run_tests/performance/remote_host_build.sh

tools/run_tests/performance/remote_host_prepare.sh