Fix server components externals on SSR layer (#61986)
### What
Fix the externals resolving for server rendering layer for app router.
For SSR requests, if it's next externals, we resolved and return early,
if we didn't resolve, keep going through the following externals
resolving
### Why
Previously on app router's SSR bundling layer, we didn't go through the
following requests when seeing an server external package, it will keep
bundling even it's in server components external packages.
A bug found in #61983
Closes NEXT-2473
