fix(agentgateway): address Nicole review feedback on PR #220

[tiagoek]

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

Addresses Nicole's review comments on PR #220 (Transparent TLS + ServiceBinding Envelope Support). Stacked on feat/transparent-tls-smahr (same pattern as #230).

Changes:

• Delete src/sap_cloud_sdk/core/_telemetry_compat.py and restore direct sap_cloud_sdk.core.telemetry imports in agentgateway/destination modules (telemetry remains a required dependency; use CLOUD_SDK_OTEL_DISABLED=true to disable locally)
• Remove unrelated test-agent/ entry from .gitignore
• Revert unnecessary import reorder in tests/agentgateway/unit/test_lob.py
• Keep package version at 0.33.18 (unchanged)

Related Issue

No GitHub/Jira issue yet (follow-up cleanup for #220).

Type of Change

Please check the relevant option:

• 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

Describe how reviewers can test your changes:

1. uv sync --group dev
2. uv run pytest -m "not integration" tests/agentgateway/unit/ tests/destination/unit/ -q
3. Expected result: all unit tests pass; no imports of _telemetry_compat

Checklist

Before submitting your PR, please review and check the following:

• 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
• All tests pass locally
• I have verified that my code follows the Code Guidelines
• I have updated documentation (if applicable)
• I have added type hints for all public APIs
• My code does not contain sensitive information (credentials, tokens, etc.)
• I have followed Conventional Commits for commit messages

Breaking Changes

None.

Additional Notes

• Depends on / stacks onto feat/transparent-tls-smahr (content of feat: transparent tls + service binding envelope support for agent gateway module #220 + fix(agentgateway): address sdk-review quality findings from PR #220 #230).
• Prashant's review comments on feat: transparent tls + service binding envelope support for agent gateway module #220 are out of scope for this PR (owner: original author).
• Local verification: 2662 unit tests passed (-m "not integration"), coverage 90%, uv build produced sap_cloud_sdk-0.33.18.