[receiver/mongodbreceiver] Fix index access count error collection on a replica local database

[JonathanWamsley]

Description:

The scraper is reporting a scraper error Unauthorized when trying to collect index stats when the database is local. This occurs even when the correct roles are used.

This is for the metric mongodb.index.access.count which is The number of times an index has been accessed.. This is metric is to help monitor the amount an index has been access on user created indexes, not on internal databases such as the local database. The local database in MongoDB is used for internal purpose by MongoDB which manages replication, sharding and storage and should not be used directly by users. Furthermore, the local database is invisible to replication; collections in the local database are not replicated which is causing errors when attempting to do so.

Link to tracking Issue:
#21114

Testing:
Updated integration test so they are not showing no mongodb.index.access.count metric with local database being collected.
Documentation: