Fix get_timezone call on exports download page

[esoergel]

Product Description

Fix 500 error on exports page

Technical Summary

https://dimagi.sentry.io/issues/5479646311/?environment=staging&project=136860&query=is%3Aunresolved+issue.priority%3A[high%2C+medium]&referrer=issue-stream&statsPeriod=1h&stream_index=0
Introduced in #34734
In 9f1a31c, I removed a helper function that was a near duplicate (with a different function signature) of a core util, but I neglected to see if that helper function was referenced in other files. It was, and since it had the same name as the core utility, the other file, the import didn't break. Only when it was called and encountered the different function signature did it actually error.

Feature Flag

Safety Assurance

Safety story

Testing on staging now, but it's pretty straightforward

Automated test coverage

QA Plan

Rollback instructions

• This PR can be reverted after deploy with no further considerations

Labels & Review

• Risk label is set correctly
• The set of people pinged as reviewers is appropriate for the level of risk of the change