Modify logic to ensure that the cloud_RoleInstance gets populated with the k8 pod name if specified

[rads-1996]

Description

Fixes - #45532

All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

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• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[rads-1996]

Since currently there is no resource detector logic available for AKS in Otel, the user will have to set the pod name in their configuration via the OTEL_RESOURCE_ATTRIBUTES and set that to dynamically pull the K8_POD_NAME -

The code has been modified so that the K8 pod name will have precedence and then the service instance id will be checked for.

BEFORE CHANGE -

AFTER CHANGE -

[Copilot]

Pull request overview

This PR fixes cloud_RoleInstance resolution for Kubernetes/AKS by prioritizing the Kubernetes pod name when it is present, addressing inconsistent values caused by service.instance.id being set by resource detectors.

Changes:

• Update role instance resolution order to prefer k8s.pod.name over service.instance.id.
• Expand unit tests to cover the new precedence and fallback behaviors (pod name → service instance id → hostname).
• Document the bug fix in the package changelog.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
sdk/monitor/azure-monitor-opentelemetry-exporter/azure/monitor/opentelemetry/exporter/_utils.py	Changes _get_cloud_role_instance() precedence to use Kubernetes pod name first.
sdk/monitor/azure-monitor-opentelemetry-exporter/tests/test_utils.py	Updates/adds tests validating precedence and fallback behavior for role instance.
sdk/monitor/azure-monitor-opentelemetry-exporter/CHANGELOG.md	Adds an unreleased bug-fix entry describing the precedence change.