MM-8607 Add ability to turn off non-critical services when under load (#13212)

* MM-8607: add ability to turn off non-critical services under load

* server busy invalid param unit tests

* MM-8607: rename server busy endpoints

* MM-8607: handle case where App not initialized

* MM-8607: additional unit test cases per feedback.

* MM-8607: use decorator to check isbusy when adding endpoint route

* MM-8607: rename endpoints, use struct for json

* Update api4/system.go

Fix misspelled log output

Co-Authored-By: Saturnino Abril <saturnino.abril@gmail.com>

* MM-8607: fix i18n order; max seconds for server busy expiry

model/system_test.go

@@ -6,6 +6,7 @@ package model
 import (
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/require"
 )
@@ -17,3 +18,13 @@ func TestSystemJson(t *testing.T) {
 
 	require.Equal(t, "test", result.Name, "ids do not match")
 }
+
+func TestServerBusyJson(t *testing.T) {
+	now := time.Now()
+	sbs := ServerBusyState{Busy: true, Expires: now.Unix()}
+	json := sbs.ToJson()
+	result := ServerBusyStateFromJson(strings.NewReader(json))
+
+	require.Equal(t, sbs.Busy, result.Busy, "busy state does not match")
+	require.Equal(t, sbs.Expires, result.Expires, "expiry does not match")
+}