opt(schema): Optimize populateSchema() (#8068) (#8071)

[mangalaman93]

Optimize populateSchema() by avoiding repeated lock acquisition. we can get the schema for the predicate once and then check for the required field without taking a read lock.

(cherry picked from commit d935b8b)

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[coveralls]

Coverage: 64.404% (+0.003%) from 64.401% when pulling 9aba59e on aman/popschema into 4c1b575 on main.