Ensure that the code for expect_correction is valid syntax

Issues found with this:
* rubocop#13211
* rubocop#13215
* rubocop#13216
* rubocop#13219
* rubocop#13224
* rubocop#13225

I checked some repos in the rubocop org and they seem to not be affected by this change

lib/rubocop/rspec/expect_offense.rb

@@ -169,6 +169,7 @@ def expect_correction(correction, loop: true, source: nil)
         raise 'Expected correction but no corrections were made' if new_source == source
 
         expect(new_source).to eq(correction)
+        expect(@processed_source).to be_valid_syntax, 'Expected correction to be valid syntax'
       end
       # rubocop:enable Metrics/AbcSize, Metrics/MethodLength, Metrics/CyclomaticComplexity
 

spec/rubocop/cop/style/operator_method_call_spec.rb

@@ -53,6 +53,8 @@
     end
 
     it "registers an offense when using `foo.#{operator_method}(bar)`" do
+      skip('https://github.com/rubocop/rubocop/issues/13225') if operator_method == :/
+
       expect_offense(<<~RUBY, operator_method: operator_method)
         foo.#{operator_method}(bar)
            ^ Redundant dot detected.