opentelemetry-docker-tests: Refactor Docker tests to properly validate contents of exported telemetry (#5220)

* commit

* fix tox.ini so that lint-opentelemetry-test-utils does not run pytest

* refactor traces docker tests

* update uv.lock

* update uv.lock again

* commit

* small tweaks

* refactor Docker tests

* add changelog fragment

* update import error message

* fix formatting issues

* Update dependencies in tox.ini for docker-tests

Removed PyYAML and requests dependencies from docker-tests environment.

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* apply copilot suggestions

* update docker tests format

* include more test scenarios

* add 'inline_snapshot'

* slight changes to tests

* update CONTRIBUTING.md include mention of inline-snapshot

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Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>