chore(otel): raise exception if exporter unavailable

[jer96]

Description

This is a followup to #232. After speaking with @zastrowm we agreed that it is better to explicitly raise an exception if a customer relies on Strand's internally configured OTEL HTTP exporter. The goal is to avoid a situation where a customer has deployed a Strands agent to production and after #232 their telemetry is no longer being exported. The overall blast radius of this change is minimal as outlined in #232.

Related Issues

Documentation PR

Planned for a separate PR. Tracking issue: https://github.com/strands-agents/private-sdk-python-staging/issues/76

Type of Change

• Followup

Testing

• hatch fmt --linter
• hatch fmt --formatter
• hatch test --all
• Verify that the changes do not break functionality or introduce warnings in consuming repositories: agents-docs, agents-tools, agents-cli

Checklist

• I have read the CONTRIBUTING document
• I have added tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature
• My changes generate no new warnings
• Any dependent changes have been merged and published

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