We should change the error code returned by query stats when a query stats store key fails to generate here.

This was added in SERVER-94231. DEVPROD-12749 made a change to the mutational fuzzer causing errors with this code to be treated as test failures and flagged in evergreen. This is desirable behavior on master, as we'd like to triage and consider fixing these cases. However, these are not issues we are generally interested in backporting as they are most often very low impact (more tech debt than bugs).

Changing the error code on previous branches will prevent the creation of BFs for these cases that we don't care to fix (note also that these errors are never thrown in production so there is no customer risk to not detecting them).