fix(aws_cloudwatch_logs sink): increase cloudwatch logs max event size to match new aws limit of 1MB

[cahartma]

Summary

Resolves issue #22859 by increasing the max event size for cloudwatch log events to ~ 1MB. This matches the new limit updated by AWS.

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

How did you test this PR?

Added one unit test but so far no functional tests have been run.

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the "no-changelog" label to this PR.

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References

• Closes: Increase AWS Cloudwatch Logs record limit to 1MB #22859

[pront]

Thanks @cahartma