[Bug] setters do not run on setDefaultsOnInsert

[AbdelrahmanHafez]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the issue has not already been raised

Issue

re #16049 (comment)

Setters should run with setDefaultsOnInsert

'use strict';

const mongoose = require('mongoose');
const { Schema } = mongoose;
const assert = require('assert');
const { MongoMemoryServer } = require('mongodb-memory-server');

run().catch(err => {
  console.error(err);
  process.exit(1);
});

async function run() {
  const mongod = await MongoMemoryServer.create();

  try {
    await mongoose.connect(mongod.getUri(), { dbName: 'test' });

    const schema = new Schema({
      name: String,
      slug: {
        type: String,
        default: 'Hello World!',
        set: function(v) {
          return v.toLowerCase().replace(/[^a-z0-9]+/g, '-').replace(/(^-|-$)/g, '');
        }
      }
    });
    const Test = mongoose.model('Test', schema);

    // Normal document creation: setter runs on default
    const doc = new Test({ name: 'test' });
    assert.equal(doc.slug, 'hello-world');

    // Upsert: setter does NOT run on default
    await Test.updateOne(
      { name: 'test2' },
      { $set: { name: 'test2' } },
      { upsert: true, setDefaultsOnInsert: true }
    );
    const upserted = await Test.findOne({ name: 'test2' });
    assert.equal(upserted.slug, 'hello-world');

    console.log('PASS');
  } finally {
    await mongoose.disconnect();
    await mongod.stop();
  }
}