test(fix): use ebin path without plugins

Without the filtering that already exists in cth:ebin_path, the rebar3 plugins path may
take priority over normal dependencies.  Since we just updated hocon, and there seems to
be an older hocon among the rebar3 plugins, it started to break the test because older
hocon was getting loaded in the peer.

apps/emqx/test/emqx_common_test_helpers.erl

@@ -78,6 +78,7 @@
     start_epmd/0,
     start_peer/2,
     stop_peer/1,
+    ebin_path/0,
     listener_port/2
 ]).
 

apps/emqx/test/emqx_shared_sub_SUITE.erl

@@ -1247,7 +1247,7 @@ recv_msgs(Count, Msgs) ->
 start_peer(Name, Port) ->
     {ok, Node} = emqx_cth_peer:start_link(
         Name,
-        ebin_path()
+        emqx_common_test_helpers:ebin_path()
     ),
     pong = net_adm:ping(Node),
     setup_node(Node, Port),
@@ -1261,9 +1261,6 @@ host() ->
     [_, Host] = string:tokens(atom_to_list(node()), "@"),
     Host.
 
-ebin_path() ->
-    ["-pa" | code:get_path()].
-
 setup_node(Node, Port) ->
     EnvHandler =
         fun(_) ->