Intermittent issue: browser.name filter option not available in metric alert filter

### Environment SaaS (https://sentry.io/) ### Steps to Reproduce 1. Edit an existing metric alert 2. Click on the "Filter events" search bar 3. The option "browser.name" is available: <img width="1040" alt="Image" src="https://github.com/user-attachments/assets/1b7fd1b2-9114-4ce8-80a4-6ebf39c08ee1" /> 4. Reload the page ### Expected Result Browser.name is still available as filter option ### Actual Result The option is no longer available: <img width="1056" alt="Image" src="https://github.com/user-attachments/assets/05e2bcaf-fa8a-40e7-8e1e-c6ac15149f59" /> Sometimes reopening the alert rule options will make the option appears again, sometimes it won't be listed. ### Product Area Alerts ### Link https://dev-curumas.sentry.io/alerts/rules/?statsPeriod=1h ### DSN _No response_ ### Version _No response_