[hotfix][API/DataStream] Log the right syncDurationMillis time

[Myracle]

What is the purpose of the change

Fix the wrong log info for the var syncDurationMillis.

Brief change log

• Move the set function before the log so that the var syncDurationMillis is set.

Verifying this change

This change is a trivial rework / code cleanup 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)

[flinkbot]

CI report:

• 37d7af0 Azure: SUCCESS

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[Myracle]

@pnowojski Can you help me review the easy code? Thanks.

[pnowojski]

LGTM thanks for the fix!