Remove spec for behavior we will no longer be supporting.

Fully supporting metadata mutation is fraught with difficulties
see (rspec/rspec-rails#829 and the attempted fix in #1089).
For RSpec 3, we decided to expose `define_derived_metadata`
as an officially supported way to accomplish the sorts of
things metadata mutation was used for in RSpec 2. This spec
got left behind (since it was passing at the time, it wasn't
noticed) but isn’t something we want to support going forward
since module inclusion shouldn't mutate metadata. It’s also
getting in the way of a perf optimization I'm implementing.

spec/rspec/core/configuration_spec.rb

@@ -1530,23 +1530,6 @@ def exclude?(line)
         expect(group.included_modules).to include(mod)
       end
 
-      it "includes each one before deciding whether to include the next" do
-        mod1 = Module.new do
-          def self.included(host)
-            host.metadata[:foo] = :bar
-          end
-        end
-        mod2 = Module.new
-
-        group = RSpec.describe("group")
-
-        config.include(mod1)
-        config.include(mod2, :foo => :bar)
-        config.configure_group(group)
-        expect(group.included_modules).to include(mod1)
-        expect(group.included_modules).to include(mod2)
-      end
-
       module IncludeExtendOrPrependMeOnce
         def self.included(host)
           raise "included again" if host.instance_methods.include?(:foobar)