[ITS] truncate test_session_characteristics_zoom to min(4.0, max_zoom)

Details: at high zoom ratios, ArUco markers can become truncated and undetectable. Changed test to use a lower maximum zoom ratio, to ensure that this does not occur. This follows a similar change to test_preview_zoom.

Change-Id: I6b6a18501559a95c3a5e5b0cea6d6c61c2fc423a
Flag: TEST_ONLY
Bug: 397138931
Test: ran test_session_characteristics_zoom