Breakglass flow in web app

### TL;DR

As identified in https://github.com/abcxyz/jvs/pull/294/files#r1253404326

The UI allows `breakglass` category but will fail to generate a breakglass token. One immediate fix is to allow the [processor](https://github.com/abcxyz/jvs/blob/a02ba7d38f4b16c203d37e0d879b6c67883ec43a/pkg/justification/processor.go#L148) to create breakglass token. However, the underlying logic doesn't make sense. Breakglass should be used when JVS is down so the user can bypass it. If JVS web UI is down, there is no easy way for a user to inject a breakglass token (even though they can generate one with JVS CLI) into their web request.

Instead, I'd like to disable breakglass category in JVS web UI for now and figure out how to do breakglass in the web flow.

### Expected behavior

_No response_

### Observed behavior

_No response_

### Environment Details

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### Additional information

_No response_