Simplifications

src/core/ext/client_config/subchannel.c

src/core/ext/transport/chttp2/transport/chttp2_transport.c

src/core/ext/transport/chttp2/transport/internal.h

src/core/ext/transport/chttp2/transport/stream_lists.c

src/core/lib/iomgr/error.c

src/core/lib/transport/transport.c

src/core/lib/transport/transport.h