Remove Apache Transport

### Description

https://github.com/getsentry/sentry-java/issues/6000 just shows, the transport isn't up to our standards.

Last we checked, usage numbers were fairly low.

It's time to remove it.

For anyone seeing this and wanting to keep using it, please just copy the code over.

Start by locating the Apache Transport implementation and every reference to it in the sentry-java repository. Confirm the removal scope and identify affected tests or documentation before changing anything; done means the transport and its references are removed without breaking the remaining SDK checks.

Written by the indexing model from the issue text.