MM-36764 mlog refactor (#18118)

Refactor mlog
- simplify mlog by removing redundant code
- remove Zap dependency
- update unit test helpers
- update logging config
- update auditing

store/sqlstore/main_test.go

@@ -6,7 +6,6 @@ package sqlstore_test
 import (
 	"testing"
 
-	"github.com/mattermost/mattermost-server/v6/shared/mlog"
 	"github.com/mattermost/mattermost-server/v6/store/sqlstore"
 	"github.com/mattermost/mattermost-server/v6/testlib"
 )
@@ -14,7 +13,6 @@ import (
 var mainHelper *testlib.MainHelper
 
 func TestMain(m *testing.M) {
-	mlog.DisableZap()
 	mainHelper = testlib.NewMainHelperWithOptions(nil)
 	defer mainHelper.Close()