Remove redundant config metadata

Previously, this was needed to have control over "config" shared context
inclusion. We wanted to include ours, but not the one from `rubocop`.
This is a follow-up to #1332.

Author: pirj

spec/rubocop/cop/rspec/be_empty_spec.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-RSpec.describe RuboCop::Cop::RSpec::BeEmpty, :config do
+RSpec.describe RuboCop::Cop::RSpec::BeEmpty do
   it 'registers an offense when using `expect(array).to contain_exactly`' do
     expect_offense(<<~RUBY)
       expect(array).to contain_exactly

spec/rubocop/cop/rspec/change_by_zero_spec.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-RSpec.describe RuboCop::Cop::RSpec::ChangeByZero, :config do
+RSpec.describe RuboCop::Cop::RSpec::ChangeByZero do
   it 'registers an offense when using `change` and argument to `by` is zero' do
     expect_offense(<<-RUBY)
       it do

spec/rubocop/cop/rspec/rails/minitest_assertions_spec.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-RSpec.describe RuboCop::Cop::RSpec::Rails::MinitestAssertions, :config do
+RSpec.describe RuboCop::Cop::RSpec::Rails::MinitestAssertions do
   it 'registers an offense when using `assert_equal`' do
     expect_offense(<<~RUBY)
       assert_equal(a, b)

spec/rubocop/cop/rspec/skip_block_inside_example_spec.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-RSpec.describe RuboCop::Cop::RSpec::SkipBlockInsideExample, :config do
+RSpec.describe RuboCop::Cop::RSpec::SkipBlockInsideExample do
   it 'registers an offense when using `skip` with a block' do
     expect_offense(<<~RUBY)
       it 'does something' do