Bump OTLP errors down to warning

Following https://gitlab.cern.ch/cta/operations/-/issues/1824, OTLP errors should not be considered "true errors" (it doesn't actually affect anything of the CTA itself). As such, we should bump down these levels.

Should be trivial to do by just changing this mapping: https://gitlab.cern.ch/cta/CTA/-/blob/main/common/telemetry/CtaTelemetryLogHandler.cpp?ref_type=heads#L23