ci: clean up test workflows, keep docker-build only

.forgejo/workflows/test-docker.yml

@@ -1,19 +0,0 @@
-name: Test Docker
-
-on:
-  push:
-    branches: [main, master]
-  workflow_dispatch:
-
-jobs:
-  docker-test:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Docker version
-        run: docker version
-      - name: Docker info
-        run: docker info
-      - name: Test docker login
-        run: echo "Docker is available, checking credentials..."
-      - name: Test build
-        run: docker run --rm hello-world

.forgejo/workflows/test-runner.yml

@@ -1,15 +0,0 @@
-name: Test Runner
-
-on:
-  push:
-    branches: [main, master]
-  workflow_dispatch:
-
-jobs:
-  test:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Hello
-        run: echo "Runner is working!"
-      - name: Docker check
-        run: docker version || echo "Docker not available"