MM-40817: Use license interface in Channels (#19678)

* MM-40817: Use license interface in Channels

https://mattermost.atlassian.net/browse/MM-40817

```release-note
NONE
```

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

api4/system.go

@@ -88,7 +88,7 @@ func generateSupportPacket(c *Context, w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Checking to see if the server has a e10 or e20 license (this feature is only permitted for servers with licenses)
-	if c.App.Srv().License() == nil {
+	if c.App.Channels().License() == nil {
 		c.Err = model.NewAppError("Api4.generateSupportPacket", "api.no_license", nil, "", http.StatusForbidden)
 		return
 	}
@@ -759,7 +759,7 @@ func getWarnMetricsStatus(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	license := c.App.Srv().License()
+	license := c.App.Channels().License()
 	if license != nil {
 		mlog.Debug("License is present, skip.")
 		return
@@ -789,7 +789,7 @@ func sendWarnMetricAckEmail(c *Context, w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	license := c.App.Srv().License()
+	license := c.App.Channels().License()
 	if license != nil {
 		mlog.Debug("License is present, skip.")
 		return
@@ -831,7 +831,7 @@ func requestTrialLicenseAndAckWarnMetric(c *Context, w http.ResponseWriter, r *h
 		return
 	}
 
-	license := c.App.Srv().License()
+	license := c.App.Channels().License()
 	if license != nil {
 		mlog.Debug("License is present, skip.")
 		return