Fix flawed logic in calculation of top query metrics collection window

[sv-splunk]

Description

Issue area -1
Based on current implementation the EffectiveLookbackTime is calculated as 2 x cfg.ControllerConfig.CollectionInterval which is wrong.

Below are the default values,

ControllerConfig's CollectionInterval = 10 * time.Second
TopQueryCollection's CollectionInterval = 1 minute.

With the existing logic the EffectiveLookbackTime will be calculated as 20 seconds (2 x 10 =20), and this will not cover the previous 1 minute collection window of top_query.

Issue area -2
And the logic to determine the window slot needs to be fixed too.
The collection latency (mostly a few milliseconds) is not taken into account when the next check is done. As a result when the top_query is configured to collect at 60 seconds, practically the collection is done only by next cycle at 80 seconds.

Fix Proposal

The logic should have been 2 X TopQueryCollection's CollectionInterval to effectively cover the collection period.

And to determine the window,

current check: if s.lastExecutionTimestamp.Add(s.config.TopQueryCollection.CollectionInterval).After(time.Now()) {...}

proposed fix: if int(math.Ceil(time.Since(s.lastExecutionTimestamp).Seconds())) < int(s.config.TopQueryCollection.CollectionInterval.Seconds()) {...}

Link to tracking issue

Fixes #44162

Testing

Documentation

[otelbot]

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