Reduce frames of burst capture

Reduce ION memory required by ITS test case to prevent memory low
issues.

Bug: 122574616
Change-Id: I8e076991e6da2caf341d7edc89a827511a2a20d7
Signed-off-by: Xinghua Yang <xinghua.yang@mediatek.com>
diff --git a/apps/CameraITS/tests/scene0/test_burst_capture.py b/apps/CameraITS/tests/scene0/test_burst_capture.py
index e6ee100..f915a6a 100644
--- a/apps/CameraITS/tests/scene0/test_burst_capture.py
+++ b/apps/CameraITS/tests/scene0/test_burst_capture.py
@@ -23,7 +23,7 @@
        of fullsize capture + CPU read for at least some time.
     """
     NAME = os.path.basename(__file__).split(".")[0]
-    NUM_TEST_FRAMES = 20
+    NUM_TEST_FRAMES = 15
 
     with its.device.ItsSession() as cam:
         props = cam.get_camera_properties()