fix(test): drop redundant user.email index setup

ensure_tables already adds the email index; a second add_table_index
aborted with {already_exists,user,3} and failed the suite setup.

test/unit/core_user_tests.erl

@@ -6,12 +6,8 @@
 
 setup() ->
   eh_test_support:start_mnesia(),
+  %% email index comes from eh_test_support:ensure_indexes/1
   eh_test_support:ensure_tables(?TABLES),
-  case mnesia:add_table_index(user, email) of
-    {atomic, ok} -> ok;
-    {aborted, {already_exists, user, email}} -> ok;
-    {aborted, Reason} -> error({add_index_failed, Reason})
-  end,
   ok.
 
 cleanup(_) ->

test/unit/logic_user_tests.erl

@@ -12,12 +12,8 @@
 
 setup() ->
   eh_test_support:start_mnesia(),
+  %% email index comes from eh_test_support:ensure_indexes/1
   eh_test_support:ensure_tables(?TABLES),
-  case mnesia:add_table_index(user, email) of
-    {atomic, ok} -> ok;
-    {aborted, {already_exists, user, email}} -> ok;
-    {aborted, Reason} -> error({add_index_failed, Reason})
-  end,
   ok.
 
 cleanup(_) ->