Remove extra source positions added by Liftoff to help with OSR. Compute
the return address based on the call source position instead.

R=clemensb@chromium.org

Bug: v8:10337
Change-Id: Ifc14e924825b670ebaed920bb19d0fa09eca1b23
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2351666Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69359}