[FLINK-36963][Runtime] Fix wrong context maintain around asyncProcessWithKey

[Zakelly]

What is the purpose of the change

Within asyncProcessWithKey, the key/record context is switched to the one for asynchronous procedure then switched back. However we picked the wrong old context and switched back with the wrong one. This PR fixes that.

Brief change log

• The asyncProcessWithKey of both related operators.

Verifying this change

This change is a trivial rework without any test coverage.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not applicable

[fredia]

Thanks for the fix,LGTM.

[flinkbot]

CI report:

• b582489 Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot run azure re-run the last Azure build

[Zakelly]

@flinkbot run azure