Missing parameters 'rate' and 'count' for GCP Stackdriver Scaler alignment

### Proposal

- Add missing case for "rate" parameter in the alignerFromString function
- Add missing case for "count" parameter in the reducerFromString function

from : ./pkg/scalers/gcp/gcp_stackdriver_client.go

### Use-Case

_No response_

### Is this a feature you are interested in implementing yourself?

Yes

### Anything else?

_No response_