Remove redundant test for lookup

This reverts PART of commit ee27f3d.
thanks @clemens
https://github.com/svenfuchs/i18n/pull/282/files#r37780129

lib/i18n/tests/lookup.rb

@@ -6,7 +6,7 @@ module Lookup
       def setup
         super
         I18n.backend.store_translations(:en, :foo => { :bar => 'bar', :baz => 'baz' }, :falsy => false, :truthy => true,
-          :string => "a", :array => %w(a b c), :interpolate_array => %w(foo %{bar}), :hash => { "a" => "b" })
+          :string => "a", :array => %w(a b c), :hash => { "a" => "b" })
       end
 
       test "lookup: it returns a string" do
@@ -21,10 +21,6 @@ def setup
         assert_equal(%w(a b c), I18n.t(:array))
       end
 
-      test "lookup: it returns the interpolate_array" do
-        assert_equal ['foo', '%{bar}'], I18n.t(:interpolate_array)
-      end
-
       test "lookup: it returns a native true" do
         assert I18n.t(:truthy) === true
       end