[FLINK-39790][state/metrics] Fix State latency/size tracking metrics not exported without sampling

[Efrat19]

What is the purpose of the change

Previousely when set to

state.*-track.keyed-state-enabled: true
state.*-track.sample-interval: 1

Metrics were not exported because for sampleInterval of 1, StateMetricBase#loopUpdateCounter will always return 0.

Brief change log

• StateMetricBase#loopUpdateCounter to always return 1 if sampleInterval = 1

Verifying this change

This change added tests and can be verified as follows:

• A test to verify datapoint are reported to the histogram even when sampleInterval = 1

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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Was generative AI tooling used to co-author this PR?

no

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CI report:

• 7811eb2 Azure: SUCCESS

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