feat: expose keda_scaler_metrics_value metric for scaledJob

[woehrl01]

Provide a description of what has been changed

Currently keda_scaler_metrics_value is only exposed for ScaledObjects, but not for ScaledJobs I don't see a reason why the metric should not be exposed for ScaledJobs, too. So this PR adds that metric.

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[JorTurFer]

You are right and we should expose the metrics, but current metric is attached to ScaledObject (it has a label named scaledObject), I'd say that we should create a new metric for unifying both, splitting them by label. e.g: internal_scale_loop

Could you add a test for the new metric too? There are test cases for prometheus and otel: https://github.com/kedacore/keda/tree/main/tests/sequential

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