New Timespan For Issue Frequency

### Problem Statement

Having support for 30 min issue frequency as shown in the screenshot. This would be helpful for folks who have company goals of detecting a certain number of issues within a said amount of time. Additionally, this is something that Rollbar alerts support where you can get a notification after a certain number of unique users run into a certain issue in a 30 min moving window. [https://docs.rollbar.com/docs/notifications](https://docs.rollbar.com/docs/notifications)


### Solution Brainstorm

_No response_

### Product Area

Alerts

┆Issue is synchronized with this [Jira Improvement](https://getsentry.atlassian.net/browse/FEEDBACK-2240) by [Unito](https://www.unito.io)