Update opentelemetry to 0.18 and make it optional via a feature

[arthurprs]

What problem are we solving?

• openteletry support is using a very old version
• openteletry might be unnecessary to most users, and there's precedent (prometheus metrics) for making such things optional with features.

How are we solving the problem?

Update opentelemetry to 0.18 and make it optional via a feature

Checks

Please check these off before promoting the pull request to non-draft status.

• All CI checks are green.
• I have reviewed the proposed changes myself.

[kushudai]

Hi @arthurprs,
Thank you for this change. Could you sign the CLA so I can accept it?

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[arthurprs]

I have read the CLA Document and I hereby sign the CLA

[kushudai]

Thank you! I will merge this and release a new version with all the breaking changes this week.