Rewriting core tests BUILD files to use the build system.

bazel/grpc_build_system.bzl

test/core/bad_client/BUILD

test/core/bad_ssl/BUILD

test/core/census/BUILD

test/core/channel/BUILD

test/core/client_channel/BUILD

test/core/client_channel/resolvers/BUILD

test/core/compression/BUILD

test/core/end2end/BUILD

test/core/end2end/fuzzers/BUILD

test/core/fling/BUILD

test/core/handshake/BUILD

test/core/http/BUILD

test/core/iomgr/BUILD

test/core/json/BUILD

test/core/nanopb/BUILD

test/core/network_benchmarks/BUILD

test/core/security/BUILD

test/core/slice/BUILD

test/core/support/BUILD