Revert of Fix async/await memory leak (patchset #5 id:80001 of https://codereview.chromium.org/2334323006/ )

Reason for revert:
newly introduced test async-await-loop times out: https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20arm64%20-%20sim%20-%20MSAN/builds/10894/steps/Ignition%20-%20turbofan%20%28flakes%29/logs/async-await-loop

Original issue's description:
> Fix async/await memory leak
>
> This patch closes a memory leak in async/await where the desugaring
> was creating a situation analagous to that described in v8:5002.
> Intermediate Promises were being kept alive, so a long-running loop
> would cause linear memory usage on the heap. This patch returns
> undefined to the 'then' callback passed into PerformPromiseThen
> in order to avoid this hazard. Test expectations are fixed to remove
> expecting extraneous events which occurred on Promises that are
> now not given unnecessarily complex resolution paths before being
> thrown away.
>
> BUG=v8:5390
>
> Committed: https://crrev.com/a0ba18e9634c5e2d439033ab61a77cff54f9af35
> Cr-Commit-Position: refs/heads/master@{#39479}

TBR=adamk@chromium.org,caitp@igalia.com,littledan@chromium.org
NOTRY=true
BUG=v8:5390

Review-Url: https://codereview.chromium.org/2354473002
Cr-Commit-Position: refs/heads/master@{#39493}