test(FN-2360): harden test isolation around repo fusion state

packages/plugin-sdk/vitest.config.ts

@@ -1,5 +1,6 @@
 import { defineConfig } from "vitest/config";
 import { cpus } from "node:os";
+import { resolve } from "node:path";
 import { fileURLToPath } from "node:url";
 
 const defaultMaxWorkers = Math.max(1, cpus().length - 1);
@@ -15,6 +16,8 @@ export default defineConfig({
   },
   test: {
     include: ["src/**/*.test.ts"],
+    setupFiles: [resolve(__dirname, "../core/src/__test-utils__/vitest-setup.ts")],
+    globalSetup: [resolve(__dirname, "../core/src/__test-utils__/vitest-teardown.ts")],
     pool: "threads",
     maxWorkers,
     poolOptions: { threads: { minThreads: 1, maxThreads: maxWorkers }, forks: { minForks: 1, maxForks: maxWorkers } },