Fix accidental early evaluation of imported `using` binding (#54956)
In `using A.B`, we need to evaluate `A.B` to add the module to the using
list. However, in `using A: B`, we do not care about the value of `A.B`,
we only operate at the binding level. These two operations share a code
path and the evaluation of `A.B` happens early and is unused on the
`using A: B` path. I believe this was an unintentional oversight when
the latter syntax was added. Fixes #54954.