[SPARK-33223][SS][FOLLOWUP] Clarify the meaning of "number of rows dropped by watermark" in SS UI page

[HeartSaVioR]

What changes were proposed in this pull request?

This PR fixes the representation to clarify the meaning of "number of rows dropped by watermark" in SS UI page.

Why are the changes needed?

Aggregated Number Of State Rows Dropped By Watermark says that the dropped rows are from the state, whereas they're not. We say "evicted from the state" for the case, which is "normal" to emit outputs and reduce memory usage of the state.

The metric actually represents the number of "input" rows dropped by watermark, and the meaning of "input" is relative to the "stateful operator". That's a bit confusing as we normally think "input" as "input from source" whereas it's not.

Does this PR introduce any user-facing change?

Yes, UI element & tooltip change.

How was this patch tested?

Only text change in UI, so we know how thing will be changed intuitively.

[HeartSaVioR]

cc. @zsxwing @xuanyuanking @gaborgsomogyi as reviewers & author of #30151

[SparkQA]

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[SparkQA]

Test build #131396 has finished for PR 30439 at commit ec1fba1.

• This patch passes all tests.
• This patch does not merge cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #131397 has finished for PR 30439 at commit d700231.

• This patch fails due to an unknown error code, -9.
• This patch merges cleanly.
• This patch adds no public classes.

[HeartSaVioR]

retest this, please

[gaborgsomogyi]

LGTM. Yeah, that's the accurate meaning, thanks!

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Kubernetes integration test starting
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Kubernetes integration test status success
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[SparkQA]

Test build #131408 has finished for PR 30439 at commit d700231.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[dongjoon-hyun]

Thank you, @HeartSaVioR and @gaborgsomogyi .

+1, LGTM. For me, this PR is ready for merging for Apache Spark 3.1.0.

Do you have something more, @HeartSaVioR ?

[dongjoon-hyun]

I'll leave this PR to you, @HeartSaVioR .

[HeartSaVioR]

Thanks all for reviewing. Given this change is just a textural change and the metric was added by me, I don't feel I can get further review comments. Merging to master.