[hoanle0126]

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

Description

Fixes #296

• Preserves retriesCount, maxRetriesOn503, and retryDelay configured at plugin registration as default values for reply.from() calls (previously shadowed by the inner opts argument in fastify.decorateReply('from', function (source, opts))).
• Uses nullish coalescing (??) for retriesCount and maxRetriesOn503 so setting maxRetriesOn503: 0 or retriesCount: 0 works as expected instead of falling back to 10.
• Adds retriesCount and retryDelay to FastifyReplyFromOptions and maxRetriesOn503 to FastifyReplyFromHooks in types/index.d.ts.