Remove fix_new_blobs_memoization flag

What does this MR do and why?

Removes fix_new_blobs_memoization flag

This flag has been globally enabled for a few days without any obvious performance issues.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #417632 (closed)