Alerts: Can deactivate notification endpoint in use without warning

## About the bug

**Steps to reproduce:**
List the minimal actions needed to reproduce the behavior.

In Alerts

1. Create a Threshold Check
2. Create an Endpoint
3. Create a Notification Rule
4. Return to the Endpoint
5. Deactivate it

**Expected behavior:**

Expected that upon attempting to deactivate an Endpoint, that is part of one or more active rules, that there would be a warning that the endpoint is in use. e.g. "This enpdpoint is currently used in N rule(s), do you wish to proceed?" I could then decide to proceed to deactivate it or cancel the deactivation.

**Actual behavior:**

Received no warning or notification that the endpoint is in use.

**Visual Proof:**


## About your environment

**Environment info:**

Working with remocal a project UI.

Latest commit in UI
```
commit 019ec01d3ca48826c02777043ddd76cb47ac7416
Author: karel-rehor
Date: Wed Jan 19 10:13:01 2022 +0100
```
Latest commit in K8s-IDPE
```
commit ead1db508e2afa1c713e3872b6419b3e8c771be7
Author: Hercules Mango Churchill
Date: Wed Jan 19 09:08:24 2022 +0000
```

**Config:**

**Logs:**