ci: single Shopware install into shopware_test; serialize releases

DATABASE_URL already ends in _test so the TestBootstrapper finds an installed DB and
skips its own migration run; FORCE_INSTALL (which failed with an unknown database) removed.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

.gitea/workflows/plugin-checks.yml

@@ -86,12 +86,12 @@ jobs:
         env:
           MARIADB_ROOT_PASSWORD: root
     env:
-      DATABASE_URL: mysql://root:root@database:3306/shopware
+      # Already the *_test name: Shopware's TestBootstrapper would otherwise append _test and run every migration a second time.
+      DATABASE_URL: mysql://root:root@database:3306/shopware_test
       APP_ENV: test
       APP_URL: http://localhost
       APP_SECRET: ci-secret-not-for-production
       INSTANCE_ID: ci
-      FORCE_INSTALL: '1' # TestBootstrapper then always installs its own test DB (no separate system:install)
       COMPOSER_MEMORY_LIMIT: '-1'
       COMPOSER_ALLOW_SUPERUSER: '1'
     steps:
@@ -138,8 +138,11 @@ jobs:
           echo "PLUGIN_NAME=${PLUGIN_NAME}" >> "$GITHUB_ENV"
           rm -rf "shopware/custom/plugins/${PLUGIN_NAME}"
           cp -r plugin-src "shopware/custom/plugins/${PLUGIN_NAME}"
-      # No system:install / plugin:install: Shopware's TestBootstrapper builds its own test database and
-      # installs the plugin (tests/TestBootstrap.php), so doing it here ran every migration twice.
+      # One install into shopware_test; the bootstrapper sees an installed DB, skips its own install and
+      # only activates the plugin (tests/TestBootstrap.php forces plugin installation).
+      - name: Install Shopware (once)
+        working-directory: shopware
+        run: bin/console system:install --basic-setup --create-database --force --no-interaction
       - name: Run phpunit
         working-directory: shopware
         run: vendor/bin/phpunit -c "custom/plugins/${PLUGIN_NAME}/phpunit.xml"