Port from KPluginLoader::pluginsById to KPluginMetaData::pluginById

The latter gives us only a single plugin which makes the code a bit more concise

runners/shell/autotests/shellrunnertest.cpp

@@ -37,9 +37,8 @@ void ShellRunnerTest::initTestCase()
     QStandardPaths::setTestModeEnabled(true);
     setlocale(LC_ALL, "C.utf8");
 
-    auto pluginMetaDatas = KPluginLoader::findPluginsById(QStringLiteral(PLUGIN_BUILD_DIR), QStringLiteral(RUNNER_NAME));
+    const KPluginMetaData runnerMetadata = KPluginMetaData::findPluginById(QStringLiteral(PLUGIN_BUILD_DIR), QStringLiteral(RUNNER_NAME));
-    QCOMPARE(pluginMetaDatas.count(), 1);
+    QVERIFY(runnerMetadata.isValid());
-    KPluginMetaData runnerMetadata = pluginMetaDatas.first();
     delete manager;
     manager = new RunnerManager();
     manager->setAllowedRunners({QStringLiteral(RUNNER_NAME)});