fix(http): Improve exhausted 5xx retry errors

[devin-ai-integration]

Summary

Improve the user-facing error produced when HTTP server errors still fail after all retry attempts. Instead of surfacing the generic Something went wrong in the connector fallback through retry exhaustion, retry-exhausted HTTP 500/502/503/504 responses now emit deterministic API server status messages while preserving request URL, response code, and response text in the internal message.

Resolves https://github.com/airbytehq/airbyte-internal-issues/issues/16430
Related to https://github.com/airbytehq/oncall/issues/10694

Review & Testing Checklist for Human

• Confirm the new HTTP 5xx messages match the error-message guidelines and are appropriate for connector UI display.
• Confirm preserving e.failure_type for retry-exhausted server errors keeps the intended failure classification.
• Run a low-code connector scenario with repeated HTTP 500 responses to verify the trace message shown to users is specific.

Notes

• source-salesloft is manifest-only/low-code, but the vague fallback is emitted by shared CDK HttpClient when a retryable HTTP exception exhausts retries, so the fix is at the CDK layer.
• This is not a breaking change: it does not change connector specs, schemas, state format, or public interfaces. HTTP 5xx retry exhaustion remains transient_error.
• Local checks passed in this continuation: poetry run ruff format --check airbyte_cdk/sources/streams/http/http_client.py unit_tests/sources/streams/http/test_http_client.py, poetry run ruff check airbyte_cdk/sources/streams/http/http_client.py unit_tests/sources/streams/http/test_http_client.py, and poetry run pytest unit_tests/sources/streams/http/test_http_client.py::test_send_with_retry_raises_specific_message_for_exhausted_server_error -q.
• CI is passing: 31 checks passed, 0 failed, 0 pending.

Link to Devin session: https://app.devin.ai/sessions/482d9f86c837463ab9c1720d40640fff

[devin-ai-integration]

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[github-actions]

PyTest Results (Fast)

4 060 tests  +1   4 049 ✅ +1   7m 35s ⏱️ -10s
    1 suites ±0      11 💤 ±0 
    1 files   ±0       0 ❌ ±0 

Results for commit ff6edd8. ± Comparison against base commit d3d1346.

[github-actions]

PyTest Results (Full)

4 063 tests  +1   4 051 ✅ +1   10m 55s ⏱️ -1s
    1 suites ±0      12 💤 ±0 
    1 files   ±0       0 ❌ ±0 

Results for commit ff6edd8. ± Comparison against base commit d3d1346.