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

api4/config_test.go

@@ -4,7 +4,6 @@
 package api4
 
 import (
-	"context"
 	"fmt"
 	"io/ioutil"
 	"net/http"
@@ -468,7 +467,7 @@ func TestUpdateConfigDiffInAuditRecord(t *testing.T) {
 	require.Equal(t, timeoutVal+1, *cfg.ServiceSettings.ReadTimeout)
 
 	// Forcing a flush before attempting to read log's content.
-	err = th.Server.Log.Flush(context.Background())
+	err = th.Server.Audit.Flush()
 	require.NoError(t, err)
 
 	require.NoError(t, logFile.Sync())