Merge pull request #11703 from yang-g/cq_shutdown

include/grpc/impl/codegen/grpc_types.h

src/core/ext/filters/client_channel/channel_connectivity.c

src/core/lib/surface/alarm.c

src/core/lib/surface/call.c

src/core/lib/surface/channel_ping.c

src/core/lib/surface/completion_queue.c

src/core/lib/surface/completion_queue.h

src/core/lib/surface/server.c

src/cpp/server/server_cc.cc

test/core/end2end/fuzzers/server_fuzzer.c

test/core/fling/server.c

test/core/surface/completion_queue_test.c

test/core/surface/completion_queue_threading_test.c

test/cpp/microbenchmarks/bm_cq.cc

test/cpp/microbenchmarks/bm_cq_multiple_threads.cc