Add plugin worker integration tests for erasure coding (#8450)

* test: add plugin worker integration harness

* test: add erasure coding detection integration tests

* test: add erasure coding execution integration tests

* ci: add plugin worker integration workflow

* test: extend fake volume server for vacuum and balance

* test: expand erasure coding detection topologies

* test: add large erasure coding detection topology

* test: add vacuum plugin worker integration tests

* test: add volume balance plugin worker integration tests

* ci: run plugin worker tests per worker

* fixes

* erasure coding: stop after placement failures

* erasure coding: record hasMore when early stopping

* erasure coding: relax large topology expectations

.github/workflows/plugin-workers.yml

@@ -0,0 +1,39 @@
+name: "Plugin Worker Integration Tests"
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+permissions:
+  contents: read
+
+jobs:
+  plugin-worker:
+    name: "Plugin Worker: ${{ matrix.worker }}"
+    runs-on: ubuntu-22.04
+    timeout-minutes: 10
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - worker: erasure_coding
+            path: test/plugin_workers/erasure_coding
+          - worker: vacuum
+            path: test/plugin_workers/vacuum
+          - worker: volume_balance
+            path: test/plugin_workers/volume_balance
+
+    steps:
+      - name: Set up Go 1.x
+        uses: actions/setup-go@v6
+        with:
+          go-version: ^1.26
+        id: go
+
+      - name: Check out code into the Go module directory
+        uses: actions/checkout@v6
+
+      - name: Run plugin worker tests
+        run: go test -v ./${{ matrix.path }}