Dashboards: Ad-hoc filters don't escape sensitive characters

### What happened? When using ad hoc filters in a dashboard, searching for a key that is a file path, where the value will contain backslash (such as a windows file path), grafana throws an error. <img width="571" height="167" alt="Image" src="https://github.com/user-attachments/assets/27b32a80-9d88-4661-8cad-501f54f03a58" /> <img width="429" height="63" alt="Image" src="https://github.com/user-attachments/assets/478fdce3-97c8-4b2c-9521-160893776046" /> And no data is returned ### What did you expect to happen? I expected Grafana to be able to handle all characters in a filename in ad hoc filters, in the same way it handles the same kind of filter when it is applied from a "labels selector dropdown" in the dashboard, or if using the "+"-icon next to the label when a log row is selected/expanded to filter on a label value. ### Did this work before? I don't know. Grafana does escape problematic characters automatically when the same filename filter is applied using a label-selector-dropdown or the "+"-icon in an expanded log row. ### How do we reproduce it? 1. Use a dataset where a label contains windows filepaths (or other values with backslashes) 2. Use a dashboard having an ad-hoc filter 3. Use ad hoc filter and pick a value from that label 4. Apply the filter 5. -> error message appears and no data returned ### Is the bug inside a dashboard panel? In a dashboard, but not a panel ### Environment (with versions)? Grafana 12.0.1 Server OS: Linux Client OS: Windows Browser: Edge 141.0.3537.85 ### Grafana platform? None ### Datasource(s)? Loki