Add test for Future inflating arg size to 3x

Add test for Future inflating arg size to 3x

This adds one more test that should track improvements to generator
layout, like #62958 and #62575.

In particular, this test highlights suboptimal layout, as the storage
for the argument future is not being reused across its usage as `upvar`,
`local` and `awaitee` (being polled to completion).