Fix more allocation bugs.

src/core/ext/transport/chttp2/server/chttp2_server.c

test/core/client_channel/set_initial_connect_string_test.c

test/core/end2end/bad_server_response_test.c

test/core/end2end/fixtures/http_proxy.c

test/core/iomgr/tcp_server_posix_test.c

test/core/surface/concurrent_connectivity_test.c

test/core/util/reconnect_server.c