main: rework the way the mock logger is passed

Pass the mock logger directly to `run()` instead of mocking
`logrus.New`. Doing the later leads to a data race when multiple
parallel tests modify the (global) `var logrusNew logrus.New`.

Thanks to Tomas Hozza for reporting.

cmd/osbuild-worker-executor/export_test.go

@@ -4,9 +4,6 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
-
-	"github.com/sirupsen/logrus"
-	logrusTest "github.com/sirupsen/logrus/hooks/test"
 )
 
 var (
@@ -15,19 +12,6 @@ var (
 	HandleIncludedSources = handleIncludedSources
 )
 
-func MockLogger() (hook *logrusTest.Hook, restore func()) {
-	saved := logrusNew
-	logger, hook := logrusTest.NewNullLogger()
-	logrusNew = func() *logrus.Logger {
-		return logger
-	}
-	logger.SetLevel(logrus.DebugLevel)
-
-	return hook, func() {
-		logrusNew = saved
-	}
-}
-
 func MockOsbuildBinary(t *testing.T, new string) (restore func()) {
 	t.Helper()