Reasonable prefetches for remote FS by default

[alexey-milovidov]

Changelog category (leave one):

• Performance Improvement

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Speed up reading from S3 by enabling prefetches by default.

[robot-clickhouse]

This is an automated comment for commit bdaf0d4 with description of existing statuses. It's updated for the latest CI running
The full report is available here
The overall status of the commit is 🟡 pending

Check name	Description	Status
CI running	A meta-check that indicates the running CI. Normally, it's in success or pending state. The failed status indicates some problems with the PR	🟡 pending
Mergeable Check	Checks if all other necessary checks are successful	🟢 success