[Backport 7.56.x] Fixed the heat endpoint for the Openstack Controller

[datadog-agent-integrations-bot]

Backport 5139e97 from #17996.

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What does this PR do?

We noticed that the heat stacks weren't being discovered in the Openstack Controller integration:
2024-07-03 15:55:34 UTC | CORE | DEBUG | (pkg/collector/python/datadog_agent.go:133 in LogMessage) | - | (connectionpool.py:474) | [http://10.164.0.33:80](http://10.164.0.33/) "GET /heat-api/v1/***************************87d1e/v1/***************************87d1e/stacks HTTP/1.1" 404 154 2024-07-03 15:55:34 UTC | CORE | ERROR | (pkg/collector/python/datadog_agent.go:127 in LogMessage) | openstack_controller:92e51db26f99a1e5 | (component.py:79) | HTTPError: <Response [404]>

When reading the API documentation for heat (https://docs.openstack.org/api-ref/orchestration/v1/), there is no endpoint for /v1 or /v1/{tenant_id}.

So looking at how we get the endpoint in https://github.com/DataDog/integrations-core/blob/master/openstack_controller/datadog_checks/openstack_controller/api/api_rest.py#L34, either the project_id can be removed (causing /v1 to be made the endpoint) or the project_id can be kept (causing /v1/{tenant_id} to be the endpoint).

As such, a specific edge case needed to be added for generating the endpoint for the heat component.

Motivation

Additional Notes

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Changelog entries must be created for modifications to shipped code
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged