[exporterbatcher] Update batcher to support serialized bytes based batching.

[sfc-gh-sili]

Description

This PR

1. Updates batcher to use Size(sizerType) instead of itemsCount()
2. For logs, traces, and metrics, it also makes sure that the cachedSize is associated with the sizerType.

This will be followed by https://github.com/open-telemetry/opentelemetry-collector/pull/12635/files which enables turning on this feature from configuration.

Link to tracking issue

#3262

Testing

Documentation

[codecov]

Codecov Report

Attention: Patch coverage is 85.04673% with 16 lines in your changes missing coverage. Please review.

Project coverage is 91.46%. Comparing base (eb00c82) to head (ca7fc03).

Files with missing lines	Patch %	Lines
exporter/exporterhelper/logs.go	87.50%	3 Missing ⚠️
exporter/exporterhelper/metrics.go	87.50%	3 Missing ⚠️
exporter/exporterhelper/traces.go	87.50%	3 Missing ⚠️
...xporter/exporterhelper/xexporterhelper/profiles.go	57.14%	3 Missing ⚠️
...orterhelper/internal/queuebatch/default_batcher.go	83.33%	2 Missing ⚠️
...ter/exporterhelper/internal/requesttest/request.go	0.00%	2 Missing ⚠️

❌ Your patch check has failed because the patch coverage (85.04%) is below the target coverage (95.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12641      +/-   ##
==========================================
- Coverage   91.50%   91.46%   -0.05%     
==========================================
  Files         480      480              
  Lines       26464    26522      +58     
==========================================
+ Hits        24217    24259      +42     
- Misses       1778     1794      +16     
  Partials      469      469              

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[bogdandrutu]

Where is this used?

[sfc-gh-sili]

Removed.

[bogdandrutu]

Better to have 2 values than this map which needs heap allocation and lookup is more expensive.

[bogdandrutu]

this design seems a bit off to return -1 here. At least document this behavior.

[sfc-gh-sili]

I changed -1 to 0 and documented the behavior. Alternative is to panic if the sizer is unknown but I am reluctant to have any panic in the code