Update CHANGELOGs for time changes in metrics aggregations

[fraillt]

Changes

Update CHANGELOG in sdk and stdout crates, to reflect breaking changes made on metric aggregations.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[fraillt]

It's worth noting, that currently #2411 is not closed yet, even though it's mentioned in CHANGELOG already.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.3%. Comparing base (d0ef365) to head (5235bcc).
Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2412   +/-   ##
=====================================
  Coverage   79.3%   79.3%           
=====================================
  Files        122     122           
  Lines      21569   21569           
=====================================
  Hits       17114   17114           
  Misses      4455    4455           

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[cijothomas]

I think this is okay to skipp changelog for stdout

[fraillt]

I think it's important to mention this... I mean, my company use similar approach in production (have custom exporter that exports metrics as logs using log instead println). So I imagine that someone might rely on the format of stdout exporter.

[cijothomas]

So I imagine that someone might rely on the format of stdout exporter.

I don't think so. It's explicitly called out that stdout is only for learning purposes, and its output format should not be relied upon for anything.

https://github.com/open-telemetry/opentelemetry-rust/blob/main/opentelemetry-stdout/src/lib.rs#L1-L4

(Not a blocker for this PR, just sharing that stdout is not meant for that purpose)