optimization(fetch) pause/resume sockets in the pool

[cirospaciari]

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 12:20 PM PT - Apr 9th, 2025}

❌ @cirospaciari, your commit e8bee70 has 3 failures in Build #14723:

• test/js/bun/http/serve-body-leak.test.ts - 2 failing on 🐧 3.21 aarch64
• test/js/bun/http/serve-body-leak.test.ts - 2 failing on 🐧 3.21 x64-baseline
• test/js/bun/http/serve-body-leak.test.ts - 2 failing on 🐧 3.21 x64
• test/js/bun/http/serve-body-leak.test.ts - timeout on 🍎 14 x64
• test/js/third_party/body-parser/express-memory-leak.test.ts - 3 failing on 🍎 13 aarch64
• test/js/third_party/body-parser/express-memory-leak.test.ts - 3 failing on 🍎 14 aarch64
• test/js/third_party/body-parser/express-memory-leak.test.ts - timeout on 🍎 13 x64
• test/js/third_party/body-parser/express-memory-leak.test.ts - timeout on 🍎 14 x64
• test/js/web/fetch/fetch.test.ts - 1 failing on 🍎 14 aarch64

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🧪   try this PR locally:

bunx bun-pr 18874