Remove trailing zeroes when setting "decimals"

**Why is this needed**: When manually setting the decimal precision via the `decimals` option the trailing zeroes are never removed, which is the default behaviour when `decimals` option is not set. **What would you like to be added**: Would like an option to force the removal of trailing zeroes for when the `decimals` option is set. **Who is this feature for?** For everyone using time series dashboards and would like to set a certain decimal precision but still have numbers shorter without trailing zeros. One example where this can be useful is when using the [sloth dashboard](https://grafana.com/grafana/dashboards/14348-slo-detail/) where we need higher precision, and reducing trailing zeroes might make the UI cleaner. <img width="1411" height="777" alt="Image" src="https://github.com/user-attachments/assets/d70255b5-39f8-4479-910d-d8027254f63e" />