Correct InternalAffairs/ProcessedSourceBufferName cop

The CI running RuboCop in Edge is failed. We correct offense for `InternalAffairs/ProcessedSourceBufferName` cop.
https://github.com/rubocop/rubocop-rspec/actions/runs/4241877273/jobs/7372656638

Follow up: rubocop/rubocop#11606

```
lib/rubocop/cop/rspec/file_path.rb:168:45: C: [Correctable] InternalAffairs/ProcessedSourceBufferName: Use file_path instead.
          File.expand_path(processed_source.buffer.name)
                                            ^^^^^^^^^^^

277 files inspected, 1 offense detected, 1 offense autocorrectable
Error: Process completed with exit code 1.
```

lib/rubocop/cop/rspec/file_path.rb

@@ -165,7 +165,7 @@ def routing_spec_path?
         end
 
         def expanded_file_path
-          File.expand_path(processed_source.buffer.name)
+          File.expand_path(processed_source.file_path)
         end
       end
     end