add "expect" to list of forbidden IPC headers (#53947)
`expect` is an unsupported header for undici: https://github.com/nodejs/undici/blob/c83b084879fa0bb8e0469d31ec61428ac68160d5/lib/core/request.js#L354 -- this filters it out so that the API routes don't throw an internal server error if that header is included.
Also added a test case for the previously submitted PR that was added for `content-length: 0`
- x-ref: #53843
Fixes #53822 (erroneously closed by a content-length issue being fixed)
