Fix flaky apiserver unit test

[sblumenthal]

What does this PR do?

Fix flaky TestUnbundledEventsTransform/unbundled_events_by_Kind:ReplicaSet_and_Reason:Killing,SuccessfulDelete test

Motivation

A change introduced by this PR also modified the test cases to validate that the bug was fixed. In doing so, another expected event was added to the expected event list, which contained a title that was already present in the list: Events from the Pod default/squirtle-8fff95dbb-tsc7v.

The test code sorts the output by event title, but sort.Slice does not guarantee that order will be preserved in the case of a collision, which is what is happening here. The end result is the test sometimes succeeds, when the ordering matches what is defined in the list, and sometimes fails, when the ordering is incorrect.

This PR changes the call from sort.Slice to sort.SliceStable, which should preserve the ordering in the event of a collision

Additional Notes

Possible Drawbacks / Trade-offs

Describe how to test/QA your changes

[pr-commenter]

Regression Detector

Regression Detector Results

Run ID: 81340902-f9bd-4233-aaff-fe1a68a12229 Metrics dashboard Target profiles

Baseline: 71768e8
Comparison: 4ea53fb

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

No significant changes in experiment optimization goals

Confidence level: 90.00%
Effect size tolerance: |Δ mean %| ≥ 5.00%

There were no significant changes in experiment optimization goals at this confidence level and effect size tolerance.

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	links
➖	tcp_syslog_to_blackhole	ingress throughput	+4.65	[-8.70, +18.00]	Logs
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	+0.86	[+0.07, +1.66]	Logs
➖	idle	memory utilization	+0.28	[+0.25, +0.31]	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	+0.00	[-0.01, +0.01]	Logs
➖	uds_dogstatsd_to_api	ingress throughput	+0.00	[-0.00, +0.00]	Logs
➖	otel_to_otel_logs	ingress throughput	-0.30	[-1.11, +0.50]	Logs
➖	file_tree	memory utilization	-0.41	[-0.48, -0.34]	Logs
➖	basic_py_check	% cpu utilization	-1.22	[-3.85, +1.42]	Logs
➖	pycheck_lots_of_tags	% cpu utilization	-2.69	[-5.05, -0.33]	Logs

Bounds Checks

perf	experiment	bounds_check_name	replicates_passed
✅	idle	memory_usage	10/10

Explanation

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

[sblumenthal]

/merge

[dd-devflow]

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[dd-devflow]

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