ITS: remove hard coded '1st' dict key.

Test masks out frames where lens is moving. In case of first
frame moving, the hard coded dictionary key will cause test
to fail.

bug: 79769974

Change-Id: Iee4e9953bad351ce2b07b4b3db46235dfa07abc8
diff --git a/apps/CameraITS/tests/scene3/test_lens_movement_reporting.py b/apps/CameraITS/tests/scene3/test_lens_movement_reporting.py
index c43ac84..6fea633 100644
--- a/apps/CameraITS/tests/scene3/test_lens_movement_reporting.py
+++ b/apps/CameraITS/tests/scene3/test_lens_movement_reporting.py
@@ -163,7 +163,8 @@
         assert np.isclose(min_sharp, max_sharp, rtol=SHARPNESS_TOL)
         # assert reported location is close to assign location for af_fd
         print 'Asserting lens location close to assigned fd for af_fd data'
-        assert np.isclose(d_af_fd[0]['loc'], d_af_fd[0]['fd'],
+        first_key = min(d_af_fd.keys())  # finds 1st non-moving frame
+        assert np.isclose(d_af_fd[first_key]['loc'], d_af_fd[first_key]['fd'],
                           rtol=POSITION_TOL)
 
         # assert reported location is close for min_fd captures