fix: free VirtualMachine's mimalloc arena in debug builds

[DonIsaac]

What does this PR do?

• Documentation or TypeScript types (it's okay to leave the rest blank in this case)
• Code changes

How did you verify your code works?

[robobun]

^{Updated 4:32 PM PT - Jan 21st, 2025}

❌ @DonIsaac, your commit f9c4c1c has 7 failures in #10325:

• test/js/node/test/parallel/test-http-chunk-problem.js - code 1 on 🐧 24.04 x64-baseline
• test/js/web/fetch/fetch-leak.test.ts - 1 failing on 🪟 2019 x64-baseline
• test/js/web/fetch/fetch-leak.test.ts - 1 failing on 🪟 2019 x64
• test/js/node/worker_threads/worker_threads.test.ts - segmentation fault on 🐧 3.20 aarch64
• test/js/node/worker_threads/worker_threads.test.ts - segmentation fault on 🍎 14 x64
• test/cli/hot/hot.test.ts - timeout on 🪟 2019 x64-baseline
• test/cli/hot/hot.test.ts - timeout on 🪟 2019 x64
• test/cli/hot/hot.test.ts - timeout on 🍎 14 x64
• test/cli/hot/hot.test.ts - timeout on 🍎 14 aarch64
• test/cli/hot/hot.test.ts - timeout on 🐧 22.04 x64
• test/cli/hot/hot.test.ts - timeout on 🐧 24.04 x64
• test/cli/hot/hot.test.ts - timeout on 🐧 12 x64
• test/cli/hot/hot.test.ts - timeout on 🐧 20.04 x64
• test/cli/hot/hot.test.ts - timeout on 🍎 13 x64
• test/cli/hot/hot.test.ts - timeout on 🍎 13 aarch64
• test/cli/hot/hot.test.ts - timeout on 🐧 20.04 aarch64
• test/cli/hot/hot.test.ts - timeout on 🐧 22.04 aarch64
• test/cli/hot/hot.test.ts - timeout on 🐧 12 aarch64
• test/cli/hot/hot.test.ts - timeout on 🐧 24.04 aarch64
• test/cli/hot/hot.test.ts - timeout on 🐧 3.20 aarch64
• test/cli/hot/hot.test.ts - timeout on 🐧 20.04 x64-baseline
• test/cli/hot/hot.test.ts - timeout on 🐧 22.04 x64-baseline
• test/cli/hot/hot.test.ts - timeout on 🐧 3.20 x64
• test/cli/hot/hot.test.ts - timeout on 🐧 3.20 x64-baseline
• test/cli/hot/hot.test.ts - timeout on 🐧 24.04 x64-baseline
• test/cli/hot/hot.test.ts - timeout on 🐧 12 x64-baseline
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🪟 2019 x64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 12 x64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 22.04 x64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 24.04 x64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 20.04 x64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - SIGILL on 🍎 14 x64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 24.04 aarch64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 22.04 aarch64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 20.04 aarch64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🍎 13 x64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 3.20 aarch64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 12 aarch64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 20.04 x64-baseline
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 24.04 x64-baseline
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 3.20 x64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 12 x64-baseline
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🍎 14 aarch64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 3.20 x64-baseline
• test/js/web/broadcastchannel/broadcast-channel.test.ts - SIGTRAP on 🍎 13 aarch64
• test/js/web/broadcastchannel/broadcast-channel.test.ts - segmentation fault on 🐧 22.04 x64-baseline
• test/js/node/worker_threads/worker_destruction.test.ts - segmentation fault at address 0x3d7605f0000 on 🪟 2019 x64-baseline
• test/js/node/worker_threads/worker_destruction.test.ts - segmentation fault at address 0x31ade620000 on 🪟 2019 x64
• test/js/web/workers/worker.test.ts - segmentation fault on 🪟 2019 x64-baseline
• test/js/web/workers/worker.test.ts - segmentation fault on 🪟 2019 x64
• test/js/web/workers/worker.test.ts - segmentation fault on 🐧 24.04 aarch64
• test/js/web/workers/worker.test.ts - segmentation fault on 🐧 22.04 aarch64
• test/js/web/workers/worker.test.ts - segmentation fault on 🐧 3.20 aarch64
• test/js/web/workers/worker.test.ts - segmentation fault on 🐧 3.20 x64

---

🧪   try this PR locally:

bunx bun-pr 16576

[DonIsaac]

• wip: leaked JSGlobalObject in worker threads #16578
• fix: un-ref'd source map causing memory leak #16577
• fix: free VirtualMachine's mimalloc arena in debug builds #16576 👈 (View in Graphite)
• main

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