MM-52712: Prevent CI cancellation in master (round 2) (#23293)

We discovered that cancel-in-progress only controls
in-progress jobs. Which means that pending jobs will _always_
be cancelled regardless. There is an open discussion:
https://github.com/orgs/community/discussions/5435
which was closed saying this is how the feature is designed.

We try to work around this by refactoring into separate reusable
workflows and having concurrency only for PR workflows.

```release-note
NONE
```

Co-authored-by: Mattermost Build <build@mattermost.com>

.github/workflows/server-test-template.yml

@@ -0,0 +1,57 @@
+name: Server Test Template
+on:
+  workflow_call:
+    inputs:
+      datasource:
+        required: true
+        type: string
+      drivername:
+        required: true
+        type: string
+env:
+  go-version: "1.19.5"
+jobs:
+  test:
+    runs-on: ubuntu-latest-8-cores
+    env:
+      COMPOSE_PROJECT_NAME: ghactions
+      BUILD_IMAGE: mattermost/mattermost-build-server:20230118_golang-1.19.5
+    steps:
+      - name: Checkout mattermost-server
+        uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c # v3.3.0
+      - name: Setup Go
+        uses: actions/setup-go@4d34df0c2316fe8122ab82dc22947d607c0c91f9 # v4.0.0
+        with:
+          go-version: ${{ env.go-version }}
+          cache-dependency-path: server/go.sum
+      - name: Run docker compose
+        run: |
+          cd server/build
+          docker-compose --no-ansi run --rm start_dependencies
+          cat ../tests/test-data.ldif | docker-compose --no-ansi exec -T openldap bash -c 'ldapadd -x -D "cn=admin,dc=mm,dc=test,dc=com" -w mostest';
+          docker-compose --no-ansi exec -T minio sh -c 'mkdir -p /data/mattermost-test';
+          docker-compose --no-ansi ps
+          cd ..
+      - name: Wait for docker compose
+        run: |
+          until docker network inspect ghactions_mm-test; do echo "Waiting for Docker Compose Network..."; sleep 1; done;
+          docker run --net ghactions_mm-test appropriate/curl:latest sh -c "until curl --max-time 5 --output - http://mysql:3306; do echo waiting for mysql; sleep 5; done;"
+          docker run --net ghactions_mm-test appropriate/curl:latest sh -c "until curl --max-time 5 --output - http://elasticsearch:9200; do echo waiting for elasticsearch; sleep 5; done;"
+      - name: Run Tests
+        run: |
+          if [[ ${{ github.ref_name }} == 'master' ]]; then
+            export RACE_MODE="-race"
+          fi
+          mkdir -p client/plugins
+          cd server/build
+          docker run --net ghactions_mm-test \
+            --ulimit nofile=8096:8096 \
+            --env-file=dotenv/test.env \
+            --env MM_SQLSETTINGS_DRIVERNAME="${{ inputs.drivername }}" \
+            --env MM_SQLSETTINGS_DATASOURCE="${{ inputs.datasource }}" \
+            --env TEST_DATABASE_MYSQL_DSN="${{ inputs.datasource }}" \
+            --env TEST_DATABASE_POSTGRESQL_DSN="${{ inputs.datasource }}" \
+            -v ~/work/mattermost-server:/mattermost-server \
+            -w /mattermost-server/mattermost-server/server \
+            $BUILD_IMAGE \
+            make test-server$RACE_MODE BUILD_NUMBER=$GITHUB_HEAD_REF-$GITHUB_RUN_ID TESTFLAGS= TESTFLAGSEE=