test(destination): skip flaky http client test on non-2xx echo response

[jplbrun]

Disclaimer: Do not include SAP-internal or customer-specific information in this PR (e.g. internal system URLs, customer names, tenant IDs, or confidential configurations). This is a public repository.

Description

Fixes a flaky destination integration test (test_destinationhttpclient_sends_an_authenticated_request_using_token_fetched_from_btp) that occasionally failed with JSONDecodeError because the test called response.json() on the reply from httpbin.org, but httpbin sometimes returned a non-JSON error body (CDN 502/503 HTML, rate-limit page)

The fix adds a response.ok check after the request: if the echo service returned a non-2xx status, pytest.skip with the status code and a body preview

Related Issue

N/A

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Code refactoring
• Dependency update

How to Test

1. uv run pytest tests/destination/integration -v

Checklist

• I have read the Contributing Guidelines
• I have verified that my changes solve the issue
• I have added/updated automated tests to cover my changes — N/A, this is
  itself a test-only change
• All tests pass locally
• I have verified that my code follows the Code Guidelines
• I have updated documentation (if applicable) — N/A
• I have added type hints for all public APIs — N/A (test code)
• My code does not contain sensitive information (credentials, tokens, etc.)
• I have followed Conventional Commits for commit messages

Breaking Changes

None

Additional Notes

None