Use committed database.yml instead of generating it in CI

The repo's config/database.yml already handles both SQLite (default) and
MySQL (DB_ADAPTER=mysql) via ERB. Remove the redundant steps that overwrote
it with a hardcoded version, and pass DB_ADAPTER=mysql for the MySQL job.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/test.yml

@@ -20,15 +20,6 @@ jobs:
         env:
           BUNDLE_WITH: "sqlite:development:test"
 
-      - name: Generate database.yml
-        run: |
-          cat > config/database.yml <<'EOF'
-          test:
-            adapter: sqlite3
-            database: db/test.sqlite3
-            pool: 5
-          EOF
-
       - name: Set up test database
         run: bin/rails db:create db:schema:load
         env:
@@ -69,27 +60,15 @@ jobs:
         env:
           BUNDLE_WITH: "mysql:development:test"
 
-      - name: Generate database.yml
-        run: |
-          cat > config/database.yml <<'EOF'
-          test:
-            adapter: mysql2
-            encoding: utf8mb4
-            collation: utf8mb4_0900_as_ci
-            database: fixin_test
-            host: 127.0.0.1
-            username: root
-            password: ""
-            pool: 5
-          EOF
-
       - name: Set up test database
         run: bin/rails db:schema:load
         env:
           RAILS_ENV: test
+          DB_ADAPTER: mysql
 
       - name: Run tests
         run: bin/rails test
         env:
           RAILS_ENV: test
           CI: "true"
+          DB_ADAPTER: mysql