[RISCV] Use DefaultAttrsIntrinsic for some vector intrinsics. (#94819)

This adds IntrWillReturn, IntrNoSync, IntrNoFree, and IntrNoCallback.
The IntrWillReturn is needed to make the intrinsic eligible for being
dead code eliminated if they are unused.

We already use this for most intrinsics. I wonder if the rounding mode
intrinsics were in review when the other intrinsics were changed to
DefaultAttrsIntrinsic.