Add support for other Keda Scalers

### Description Right now the Official Charts have support for the Keda scaler but it is limited using `postgresql` as the source of the trigger. This works great for most use cases, but sometimes it might be required to use some other scaler (for example a Prometheus metric). Technically we could add a `ScaledObject` outside of this chart to handle this but the `replicas` field in the Workers depends on whether or not you are using the charts' one, so there are conflicts in the replica count when trying to deploy. To fix it, we could either move the current configuration to the values so it can be overwritten if desired or decoupling the `replicas` field in the worker from whether `keda` is being used or not. ### Use case/motivation _No response_ ### Related issues _No response_ ### Are you willing to submit a PR? - [X] Yes I am willing to submit a PR! ### Code of Conduct - [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)