[hotfix] Fix typo in upload artifact condition

[snuyanzin]

What is the purpose of the change

there is a typo in upload artifact condition

and GHA complains with warning about that (could be seen at every action, e.g. https://github.com/apache/flink/actions/runs/26073467202)

Workflow syntax warning: .github/workflows/nightly.yml#L55
In .github/workflows/nightly.yml (Line: 55, Col: 11): Error from called workflow apache/flink/.github/workflows/template.flink-ci.yml@1e6a73616eb4e224a149e684c832f20bcba93148 (Line: 308, Col: 13): Conditional expression contains literal text outside replacement tokens. This will cause the expression to always evaluate to truthy. Did you mean to put the entire expression inside ${{ }}?

Brief change log

gha

Verifying this change

GHA: see whether warning is present

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)

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[flinkbot]

CI report:

• a24ff38 Azure: SUCCESS

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[XComp]

I didn't find the warning in your linked GHA run. But this looks like a bug, yes.

[snuyanzin]

I didn't find the warning in your linked GHA run.

you need to scroll to the bottom: the warnings are just before artifacts