[exporter][batching] Enable batching based on size

[sfc-gh-sili]

Description

This PR enable serialized batching based on size rather than item count.

Link to tracking issue

Fixes #3262

Testing

Documentation

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: sfc-gh-sili / name: Sindy Li (cc69405, f05edf8)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.01%. Comparing base (9204a06) to head (f05edf8).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #12635   +/-   ##
=======================================
  Coverage   92.01%   92.01%           
=======================================
  Files         478      478           
  Lines       26236    26238    +2     
=======================================
+ Hits        24141    24143    +2     
  Misses       1673     1673           
  Partials      422      422           

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[bogdandrutu]

I found yesterday a bug, see https://github.com/open-telemetry/opentelemetry-collector/blob/main/exporter/exporterhelper/internal/batcher/default_batcher.go#L85 and everywhere where ItemsCount is used in that file.

[jmacd]

@bogdandrutu does #12651 cover a fix for that issue? Is the bug described in an issue already?

[sfc-gh-sili]

I found yesterday a bug, see https://github.com/open-telemetry/opentelemetry-collector/blob/main/exporter/exporterhelper/internal/batcher/default_batcher.go#L85 and everywhere where ItemsCount is used in that file.

#12641 addresses this issue. It is built on top of prototype in #12651