Introducing the MaxTimeSeriesInBatch config option

[olegbespalov]

What?

Moving cloud output v2 from MaxMetricSamplesPerPackage to MaxTimeSeriesInBatch.

Why?

The new option reflects the actual purpose and usage of the config option.

Checklist

• I have performed a self-review of my code.
• I have added tests for my changes.
• I have run linter locally (make ci-like-lint) and all checks pass.
• I have run tests locally (make tests) and all tests pass.
• I have commented on my code, particularly in hard-to-understand areas.

Related PR(s)/Issue(s)

Closes #3156

[codecov-commenter]

Codecov Report

Merging #3157 (e60c721) into master (3291b98) will decrease coverage by 0.06%.
The diff coverage is 62.50%.

❗ Current head e60c721 differs from pull request most recent head c37e284. Consider uploading reports for the commit c37e284 to get more accurate results

@@            Coverage Diff             @@
##           master    #3157      +/-   ##
==========================================
- Coverage   72.80%   72.75%   -0.06%     
==========================================
  Files         255      253       -2     
  Lines       19581    19582       +1     
==========================================
- Hits        14256    14246      -10     
- Misses       4429     4434       +5     
- Partials      896      902       +6     

Flag	Coverage Δ
ubuntu	72.75% <62.50%> (+<0.01%)	⬆️
windows	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
output/cloud/output.go	75.33% <0.00%> (-1.54%)	⬇️
cloudapi/config.go	90.65% <100.00%> (+0.26%)	⬆️
output/cloud/expv2/flush.go	86.95% <100.00%> (ø)
output/cloud/expv2/output.go	66.01% <100.00%> (ø)

... and 8 files with indirect coverage changes

[codebien]

I added a few comments. Thanks for taking care.

Can you please add a validation rule like we have for the old option?

k6/output/cloud/output.go

Lines 116 to 119 in 3291b98

	if conf.MaxMetricSamplesPerPackage.Int64 < 1 {
	return nil, fmt.Errorf("metric samples per package must be a positive number but is %d",
	conf.MaxMetricSamplesPerPackage.Int64)
	}