PreloadCheck: Reset UncaughtExceptionHandler

Do not use the framework's exception handler. Rather use the default
behavior and print the exception to stdout, so that it appears in the
test failure.

Test: atest --test-mapping frameworks/base/tools/preload-check
Test: manual
Change-Id: I3563392408a72c97788452f467c027112f52f193

tools/preload-check/device/src/com/android/preload/check/Util.java

@@ -40,6 +40,8 @@ public class Util {
         } catch (Throwable t) {
             throw new RuntimeException(t);
         }
+        // Reset the framework's kill handler.
+        Thread.setDefaultUncaughtExceptionHandler(null);
     }
 
     public static Collection<DexFile> getBootDexFiles() throws Exception {