[identity] Disable external crate debug messages

Summary: This disables the debug logging for external crates on staging. This should clean up our cloudwatch logs a fair bit.

Test Plan: Tested on staging. No longer see external crate debug messages

Reviewers: varun, bartek

Reviewed By: varun

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D11850