Correct shardkey access in buildBulkWriteOps

buildBulkWriteOperations adds the shard key to
the filter condition, but it sets it to the
schema's value, not the document's value. It also
updates a problematic test, which passed because
the update value it uses was the same schema's
shard key value.

lib/model.js

@@ -3631,7 +3631,7 @@ Model.buildBulkWriteOperations = function buildBulkWriteOperations(documents, op
         const len = paths.length;
 
         for (let i = 0; i < len; ++i) {
-          where[paths[i]] = shardKey[paths[i]];
+          where[paths[i]] = document[paths[i]];
         }
       }
 

test/model.test.js

@@ -6365,9 +6365,9 @@ describe('Model', function() {
   describe('buildBulkWriteOperations() (gh-9673)', () => {
     it('builds write operations', async() => {
 
-
       const userSchema = new Schema({
-        name: { type: String }
+        name: { type: String },
+        a: { type: Number }
       }, { shardKey: { a: 1 } });
 
       const User = db.model('User', userSchema);
@@ -6386,7 +6386,7 @@ describe('Model', function() {
       const desiredWriteOperations = [
         { insertOne: { document: users[0] } },
         { insertOne: { document: users[1] } },
-        { updateOne: { filter: { _id: users[2]._id, a: 1 }, update: { $set: { name: 'I am the updated third name' } } } }
+        { updateOne: { filter: { _id: users[2]._id, a: 3 }, update: { $set: { name: 'I am the updated third name' } } } }
       ];
 
       assert.deepEqual(