chore: expose application and system metrics on the same port

[JessicaJHee]

Description

Previously there was a limitation with the OpenTelemetry adoption:

**Note**: Due to a limitation, the host and application metrics are exposed on separate ports. 
This is to be improved by making all metrics accessible on the same port (9464) in a future release. 

• This PR addresses this issue and now all metrics (both application and system) are exposed on the same port (9464).

This improved implementation is recommended by this.

• Fixes RHIDP-4404

PR acceptance criteria

Please make sure that the following steps are complete:

• GitHub Actions are completed and successful
• Unit Tests are updated and passing
• E2E Tests are updated and passing
• Documentation is updated if necessary (requirement for new features)
• Add a screenshot if the change is UX/UI related

How to test changes / Special notes to the reviewer

Verify that system and Backstage specific application metrics are both present at http://localhost:9464/metrics

[openshift-ci]

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[github-actions]

The image is available at:

• quay.io/janus-idp/backstage-showcase:pr-2039 or
• quay.io/janus-idp/backstage-showcase:pr-2039-26f89add

[github-actions]

The image is available at:

• quay.io/janus-idp/backstage-showcase:pr-2039 or
• quay.io/janus-idp/backstage-showcase:pr-2039-2d56b50b

[kim-tsao]

/test e2e-tests

[kim-tsao]

/test e2e-tests

[subhashkhileri]

/test e2e-tests

[openshift-ci]

@JessicaJHee: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/e2e-tests	2d56b50	link	true	/test e2e-tests

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.

[kim-tsao]

Force merging, since e2e test failures are unrelated and this change is already in 1.4