Don't project _id field in Mongo DB connector when it's not required

[sahoss]

Description

Currently, _id field is retrieved even when it's not necessary. We can exclude by https://www.mongodb.com/docs/drivers/java/sync/current/fundamentals/builders/projections/#exclusion-of-_id.

Fixes #17970

Release notes

(x) This is not user-visible or docs only and no release notes are required.

[sahoss]

@ebyhr addressed comments. please take a look.

[sahoss]

the tests which are failing are hive/hadoop related. 99% sure not related to this.

[Praveen2112]

Can we use Builder from MongoDB driver - https://www.mongodb.com/docs/drivers/java/sync/current/fundamentals/builders/#using-builders which has some predefined APIs we could use.

[sahoss]

Can we use Builder from MongoDB driver - https://www.mongodb.com/docs/drivers/java/sync/current/fundamentals/builders/#using-builders which has some predefined APIs we could use.

Would it be better to do it in a different PR? as otherwise this PR would be changing two things 1. excludeId 2. changing implementation of how projections are built(implementation+return type(bson(new) vs document(current)). and neither are currently directly tested. @Praveen2112
so the safer approach imo is to first modify existing code and then refactor to use bson+builder.

[sahoss]

@ebyhr @Praveen2112 can you please take a look? thanks

[ebyhr]

Could you rebase on master to resolve conflicts?