fix: whisper model billing

- Refactor model name handling across multiple controllers to improve clarity and maintainability.
- Enhance error logging and handling for better debugging and request processing robustness.
- Update pricing models in accordance with new calculations, ensuring accuracy in the billing logic.

relay/controller/helper.go

@@ -135,17 +135,6 @@ func postConsumeQuota(ctx context.Context, usage *relaymodel.Usage, meta *meta.M
 	return quota
 }
 
-func getMappedModelName(modelName string, mapping map[string]string) (string, bool) {
-	if mapping == nil {
-		return modelName, false
-	}
-	mappedModelName := mapping[modelName]
-	if mappedModelName != "" {
-		return mappedModelName, true
-	}
-	return modelName, false
-}
-
 func isErrorHappened(meta *meta.Meta, resp *http.Response) bool {
 	if resp == nil {
 		if meta.ChannelType == channeltype.AwsClaude {