Switch TiDB tests back to Docker images with Buildx caching

Replace TiUP playground with Docker-based TiDB cluster using Buildx caching:
- Use tidb-test-cluster.sh script (Docker-based cluster)
- Add Docker Buildx caching for TiDB component images (tidb, pd, tikv)
- Create Dockerfile.tidb for pulling and caching TiDB images
- Remove TiUP-related steps from workflow

Benefits:
- Docker images cached across workflow runs via Buildx GHA cache
- More consistent with MySQL/Percona/MariaDB test approach
- Better layer-level caching efficiency
- Images persist across separate workflow runs

Each TiDB test now:
1. Caches tidb, pd, and tikv images for that version using Buildx
2. Uses tidb-test-cluster.sh to start Docker-based cluster
3. Runs tests against the cluster
4. Cleans up cluster after tests

Author: zph

.github/workflows/main.yml

@@ -75,33 +75,8 @@ jobs:
       - name: Vendor Go dependencies
         run: go mod vendor
 
-      - name: Cache TiUP binary
-        id: cache-tiup-binary
-        uses: actions/cache@v4
-        with:
-          path: |
-            ~/.tiup/bin
-            ~/.tiup/manifests
-          # Cache TiUP binary separately (small, ~20MB)
-          key: ${{ runner.os }}-tiup-binary-${{ hashFiles('.github/workflows/main.yml') }}
-          restore-keys: |
-            ${{ runner.os }}-tiup-binary-
-      
-      - name: Install TiUP
-        run: |
-          if ! command -v tiup &> /dev/null; then
-            curl --proto '=https' --tlsv1.2 -sSf https://tiup-mirrors.pingcap.com/install.sh | sh
-          fi
-          echo "$HOME/.tiup/bin" >> $GITHUB_PATH
-      
-      - name: Update TiUP and playground component
-        run: |
-          export PATH=$HOME/.tiup/bin:$PATH
-          tiup update --self || true
-          tiup update playground || true
-      
-      # Note: TiDB components are NOT pre-downloaded here to avoid huge cache timeout
-      # Each test job will download and cache only the version it needs (~700-800MB per version)
+      # Note: TiDB tests now use Docker images with Buildx caching instead of TiUP
+      # Docker images are cached per version in individual test jobs
 
       - name: Pre-pull Docker images
         run: |

Dockerfile.tidb

@@ -0,0 +1,8 @@
+# Minimal Dockerfile for pulling and caching TiDB component images
+# This file is dynamically used by the workflow to pull images via Buildx
+
+ARG TIDB_COMPONENT
+ARG TIDB_VERSION
+FROM ${TIDB_COMPONENT}:${TIDB_VERSION}
+
+# No additional layers needed - just pulling the base image for caching

GNUmakefile

@@ -89,10 +89,10 @@ testtidb%:
 # WARNING: this does not work as a bare task run, it only instantiates correctly inside the versioned TiDB task run
 #          otherwise MYSQL_PORT and version are unset.
 testtidb:
-	@MYSQL_VERSION=$(MYSQL_VERSION) MYSQL_PORT=$(MYSQL_PORT) $(CURDIR)/scripts/tidb-playground.sh start || exit 1
+	@MYSQL_VERSION=$(MYSQL_VERSION) MYSQL_PORT=$(MYSQL_PORT) $(CURDIR)/scripts/tidb-test-cluster.sh --init --port $(MYSQL_PORT) --version $(MYSQL_VERSION) || exit 1
 	MYSQL_USERNAME="$(TEST_USER)" MYSQL_PASSWORD="" MYSQL_ENDPOINT=127.0.0.1:$(MYSQL_PORT) $(MAKE) testacc; \
 	TEST_RESULT=$$?; \
-	MYSQL_VERSION=$(MYSQL_VERSION) MYSQL_PORT=$(MYSQL_PORT) $(CURDIR)/scripts/tidb-playground.sh stop; \
+	MYSQL_VERSION=$(MYSQL_VERSION) MYSQL_PORT=$(MYSQL_PORT) $(CURDIR)/scripts/tidb-test-cluster.sh --destroy || true; \
 	exit $$TEST_RESULT
 
 testmariadb%: