removed useless app key 'registered' from app.src files

Summary: it's only needed by 'rebar3' and 'systools' which we don't use

Reviewed By: afterdusk

Differential Revision: D89759378

fbshipit-source-id: 2b16e2a16362d5ea551175d5102c5d32a02dfca4

Author: Alexander Shturm

src/wa_raft.app.src

@@ -9,7 +9,6 @@
     {description, "Erlang implementation of RAFT Consensus Protocol"},
     {vsn, "1.0.0"},
     {modules, []},
-    {registered, []},
     %% NOTE: No more dependency is expected for this app
     {applications, [
         kernel,