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:

4. Reload the page

### Expected Result

Browser.name is still available as filter option

### Actual Result

The option is no longer available:

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_