Update fallback for OTEL config flag

[jefchien]

Description of the issue

There are cases where the fallback to the default translated OTEL YAML path is not sufficient.

Description of changes

Adds new fallback paths to check for the OTEL config flag. Will check in the following order:

• Default translated OTEL YAML path
• Default YAML (amazon-cloudwatch-agent.yaml) in the same directory as the TOML
• Same path as the TOML, but looking for a YAML file instead (e.g. /my/favorite/config.toml → /my/favorite/config.yaml)

License

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

Tests

Added unit tests.

Requirements

Before commit the code, please do the following steps.

1. Run make fmt and make fmt-sh
2. Run make lint