Remove INTERNAL express.js spans

[mmanciop]

Given the fact that we use the opentelemetry-instrumentation-express alongside the @opentelemetry/instrumentation-http instrumentation, we create two spans per Express.js request: the SERVER span from @opentelemetry/instrumentation-http. and the INTERNAL one from opentelemetry-instrumentation-express. The upstream @opentelemetry/instrumentation-express does not provide access to the response object, so that is not an option either. We might have to write a bespoke instrumentation that adds an Express.js middleware to decorate the @opentelemetry/instrumentation-http span.