Feature request: configurable OTLP metric suffixes

[tonychoe]

Is your feature request related to a problem? Please describe.

In Cortex OTLP/HTTP ingestion, metric suffixes (e.g., _total) are always added because the behavior is effectively hard-coded to true. There is currently no configuration to disable this, which blocks use cases that require preserving original metric names.

Relevant code path indicating current hard-coded behavior:
https://github.com/cortexproject/cortex/blob/master/pkg/util/push/otlp.go#L187

Describe the solution you'd like

Introduce a configurable option in Cortex to enable or disable OTLP metric suffix injection, similar in spirit to Mimir’s otel_metric_suffixes_enabled.

Describe alternatives you've considered

• Forking or patching Cortex locally, which is undesirable from a maintenance and upgrade standpoint.

Additional context

[friedrichg]

I like it! feel free to make a PR