fix: rename subaccount id attribute

[LucasAlvesSoares]

Description

Renames the OpenTelemetry resource attribute sap.cld.subaccount_id to sap.cloud.provider.subaccount_id to align with the canonical SAP cloud attribute naming convention.

Changed files:

• src/sap_cloud_sdk/core/telemetry/constants.py — updated the ATTR_SAP_SUBACCOUNT_ID string value
• src/sap_cloud_sdk/core/telemetry/config.py — updated the corresponding docstring

All usages reference the ATTR_SAP_SUBACCOUNT_ID constant, so no other call sites required changes.

Related Issue

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

1. Run the telemetry test suite: pytest tests/core/unit/telemetry/
2. Start an instrumented app and inspect the emitted OTel resource attributes
3. Confirm the attribute key is sap.cloud.provider.subaccount_id instead of sap.cld.subaccount_id

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

[jeanscherf]

[NicoleMGomes]