Finish cleanup

src/core/iomgr/exec_ctx.c

test/core/channel/channel_stack_test.c

test/core/httpcli/httpcli_test.c

test/core/iomgr/fd_posix_test.c

test/core/iomgr/tcp_client_posix_test.c

test/core/iomgr/tcp_posix_test.c

test/core/iomgr/tcp_server_posix_test.c

test/core/iomgr/udp_server_test.c

test/core/iomgr/workqueue_test.c

test/core/security/credentials_test.c

test/core/security/jwt_verifier_test.c

test/core/security/print_google_default_creds_token.c

test/core/security/verify_jwt.c

test/core/surface/completion_queue_test.c