ITS: remove test_preview_zoom_tele z_min workaround

Details: most devices produce capture results with the minimum zoom ratio when requested, so this workaround is no longer needed.

Flag: TEST_ONLY
Bug: 395018703
Test: ran test_preview_zoom_tele

Change-Id: Ib3b6cc3c451ce517b73a6eefed49e23651dc4471