Revert "[vm/async] Don't add an <asynchronous suspension> marker along sync-async calls."

This reverts commit f4d930997b01e405b21a395c4be8dba1715d9d77.

Reason for revert: Different tests are failing on different bots.

Original change's description:
> [vm/async] Don't add an <asynchronous suspension> marker along sync-async calls.
> 
> This fixes `package:stack_trace` in the sync-start case of async/async* calls.
> 
> Change-Id: I5c41a35283439f533ab19c9fd1cc542931de4b43
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/124560
> Commit-Queue: Samir Jindel <sjindel@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>

TBR=kustermann@google.com,sjindel@google.com

Change-Id: Ib3e1b303613f0393dac6b1b81e8d1ffb322052b8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/124800
Reviewed-by: Régis Crelier <regis@google.com>
Commit-Queue: Régis Crelier <regis@google.com>