Streamline permissions check for /content given ACL/ADLS2 situations

[pamelafox]

As discussed in meeting:

The /content path currently does an initial check of Azure AI search engine to check permissions. However, if the developer is using ADLS2 either as their base data source or because they are using the user upload feature, it would be faster to check there first (as Blob storage checks tend to be very fast). We can't remove that check entirely however, as some developers many be manually setting ACLs using standard Blob storage. We could even get fancy and async-scatter-gather, but unclear if that is needed.

This will probably be easier to tackle once user upload feature is merged.

This issue is for a: (mark with an x)

- [X] bug report -> please search issues before submitting
- [ ] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)