enable full linter across the codebase (#9620)

enable linter using golangci-lint across
codebase to run a bunch of linters together,
we shall enable new linters as we fix more
things the codebase.

This PR fixes the first stage of this
cleanup.

cmd/sts-errors.go

@@ -45,12 +45,12 @@ func writeSTSErrorResponse(ctx context.Context, w http.ResponseWriter, errCode S
 	if errCtxt != nil {
 		stsErrorResponse.Error.Message = fmt.Sprintf("%v", errCtxt)
 	}
-	logKind := logger.All
+	var logKind logger.Kind
 	switch errCode {
 	case ErrSTSInternalError, ErrSTSNotInitialized:
 		logKind = logger.Minio
 	default:
-		logKind = logger.Application
+		logKind = logger.All
 	}
 	logger.LogIf(ctx, errCtxt, logKind)
 	encodedErrorResponse := encodeResponse(stsErrorResponse)