SurfaceFlinger_test: disable flaking child test

SurfaceFlinger_test.ChildLayerTest#ChildrenSurviveParentDestruction
has been breaking presubmit runs for more than one month with
no action.

Bug: 243597796
Test: SurfaceFlinger_test, TEST_MAPPING
Change-Id: I1f6b4a0756ef112624a1657246b280149a432fdd
diff --git a/TEST_MAPPING b/TEST_MAPPING
index 260ee8d..f54f132 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -56,6 +56,9 @@
         },
         {
           "include-filter": "*RefreshRateOverlayTest.*"
+        },
+        {
+          "exclude-filter": "*ChildLayerTest#ChildrenSurviveParentDestruction"
         }
       ]
     },