Deleting an instance doesn't refresh the in-app count of instances

### Current Behavior

When changing the team type, the frontend checks for any quota/usage limits for the target team type. This is based on an in-browser cached count of instances.

If a user deletes an instance, this cached count doesn't get updated. If they then go to change their team type, it may report they are exceeding the usage, even though they just deleted an instance.

Reloading the page at this point in time 'fixes' the issue - as the cached count of instances is reloaded from the backend.

### Expected Behavior

Deleting an instance should update the cached instance count and not require a page refresh.

### Steps To Reproduce

- Create a Starter team with an instance
- Delete the instance - do not reload the page
- Attempt to change team type to free tier - note the warning about being over usage (incorrect behaviour)
- Reload the page
- Attempt to change team type to free tier - note no warning is shown (correct behaviour)

### Environment

- FlowFuse version:
- Node.js version:
- npm version:
- Platform/OS:
- Browser:

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate