Add spacing between words in notifications. (#4574)

# What this PR does

Add a space between "team" and the quoted team name. Currently this
renders as:

```
This phone number has been connected to Grafana OnCall team"ops"
```

(which is an SMS I just received on my phone.)

## Which issue(s) this PR closes

Closes [issue link here]

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## Checklist

- [ ] Unit, integration, and e2e (if applicable) tests updated
- [ ] Documentation added (or `pr:no public docs` PR label added if not
required)
- [ ] Added the relevant release notes label (see labels prefixed w/
`release:`). These labels dictate how your PR will
    show up in the autogenerated release notes.

engine/apps/phone_notifications/phone_backend.py

@@ -377,7 +377,7 @@ def send_test_sms(self, user):
 
     def _notify_connected_number(self, user):
         text = (
-            f"This phone number has been connected to Grafana OnCall team"
+            f"This phone number has been connected to Grafana OnCall team "
             f'"{user.organization.stack_slug}"\nYour Grafana OnCall <3'
         )
         try:
@@ -392,7 +392,7 @@ def _notify_connected_number(self, user):
 
     def _notify_disconnected_number(self, user, number):
         text = (
-            f"This phone number has been disconnected from Grafana OnCall team"
+            f"This phone number has been disconnected from Grafana OnCall team "
             f'"{user.organization.stack_slug}"\nYour Grafana OnCall <3'
         )
         try: