test/unit_inbroker_dead_letter_SUITE.erl -> test/dead_lettering_SUITE.erl

Per discussion with @dcorbacho. Those are not unit tests as they
use Erlang client connections and manage nodes.

Author: michaelklishin

test/unit_inbroker_dead_letter_SUITE.erl renamed to test/dead_lettering_SUITE.erl

@@ -16,7 +16,7 @@
 %%
 %% For the full spec see: http://www.rabbitmq.com/dlx.html
 %%
--module(unit_inbroker_dead_letter_SUITE).
+-module(dead_lettering_SUITE).
 
 -include_lib("common_test/include/ct.hrl").
 -include_lib("kernel/include/file.hrl").