Core: Remove SettingsDatabase QObject base

Was not really needed except for the ownership.

Change-Id: I88e32123cbb85a8217ade9450b5b578845736311
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/plugins/coreplugin/settingsdatabase.cpp

@@ -68,11 +68,8 @@ public:
 } // namespace Internal
 } // namespace Core
 
-SettingsDatabase::SettingsDatabase(const QString &path,
-                                   const QString &application,
-                                   QObject *parent)
-    : QObject(parent)
-    , d(new SettingsDatabasePrivate)
+SettingsDatabase::SettingsDatabase(const QString &path, const QString &application)
+    : d(new SettingsDatabasePrivate)
 {
     const QLatin1Char slash('/');