OTEL Env vars don't respect spec

[JorTurFer]

Report

We have merged the support for OTEL metrics, but the envs used don't respect the spec:
https://opentelemetry.io/docs/specs/otel/protocol/exporter/

Expected Behavior

We should respect the spec, we use KEDA_HTTP_OTEL_HTTP_COLLECTOR_ENDPOINT when it should be OTEL_EXPORTER_OTLP_ENDPOINT (and probably supported automatically under the hood), or KEDA_HTTP_OTEL_HTTP_COLLECTOR_INSECURE instead of OTEL_EXPORTER_OTLP_INSECURE and other cases

[zorocloud]

Happy to align these if someone isn't already working on this issue.

[JorTurFer]

Thanks a lot ❤️

[zorocloud]

PR raised @JorTurFer. Shout if I've missed anything 🙂.