Description of problem:

When querying the `{BACKEND_URL}/metrics` endpoint, the backstage specific metrics such as catalog metrics no longer appear in versions of RHDH running running backstage 1.27.7+.

Tested with the `quay.io/rhdh/rhdh-hub-rhel9:1.3-46` image and was able to replicate this issue

Metrics appear properly with the `quay.io/rhdh/rhdh-hub-rhel9:1.2-132` image as well as the latest RHDH 1.2.1 image: https://catalog.redhat.com/software/containers/rhdh/rhdh-hub-rhel9/645bd4c15c00598369c31aba?container-tabs=gti&image=669fedac64fada07d4071297 

Prerequisites (if any, like setup, operators/versions):

Steps to Reproduce

1. Load an RHDH image using backstage 1.27.x+ such as `quay.io/rhdh/rhdh-hub-rhel9:1.3-46` (use either Helm Chart or Operator)
2. Query the `/metrics` endpoint
3. Observe no catalog metrics

Actual results:

No Backstage Specific Metrics:

metrics-output-for-1.3-46.txt

Expected results:

Backstage specific metrics such as in the following output example:

metrics-output-for-1.2-132.txt

Reproducibility (Always/Intermittent/Only Once):

Always

Build Details:

RHDH Version: 1.3.0

Backstage Version: 1.27.7

Upstream: https://github.com/janus-idp/backstage-showcase/tree/main @ 6c6fb537

Midstream: https://gitlab.cee.redhat.com/rhidp/rhdh/-/commits/rhdh-1-rhel-9 @ bf8b7b16

Build Time: 2024-07-30T13:56:28Z

Additional info (Such as Logs, Screenshots, etc):

• When the metrics do appear, there also came with a deprecation warning: DEPRECATED, use OpenTelemetry metrics instead
• Works on builds that use backstage v1.26.5
• This issue can also be replicated locally on the https://github.com/janus-idp/backstage-showcase project.