change the AnrDetector executor frequency from scheduleAtFixedRate to…

… scheduleWithFixedDelay

Summary:
As title.

This is a change requested by Google. Currently, we are utilizing `ExecutorService.scheduleAtFixedRate` to schedule a ANR check task. However, this approach encounters issues with newer Android versions that restrict or freeze the app. A recommended alternative is to use `scheduleWithFixedDelay`, which ensures the libary won't make up for the missed period of time, and keep the system_server healthy.

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> Newer versions of Android use the Cached App Freezer feature (see https://source.android.com/docs/core/perf/cached-apps-freezer), which pauses the execution of apps once they're in the cached state.

> scheduleAtFixedRate triggers the passed runnable periodically, which means that if an app is frozen for some time, when it's un-frozen that runnable will be called repeatedly, sometimes many (thousands) of times, depending on the requested interval.

> The behavior we actually want in this case is the behavior of scheduleWithFixedDelay, which triggers the runnable after the previous iteration has terminated. In this case, after an app is frozen for a period, we will still call the runnable upon returning from being frozen and at the desired cadence thereafter, but won't try to "make up for" the missed period of time.

Reviewed By: wx0165927473

Differential Revision: D47309581

fbshipit-source-id: 5bb44275e0376088b626bf1a03d4d7864b704c68

facebook-core/src/main/java/com/facebook/internal/instrument/anrreport/ANRDetector.kt

@@ -61,7 +61,7 @@ object ANRDetector {
   @JvmStatic
   @VisibleForTesting
   fun start() {
-    scheduledExecutorService.scheduleAtFixedRate(
+    scheduledExecutorService.scheduleWithFixedDelay(
         anrDetectorRunnable, 0, DETECTION_INTERVAL_IN_MS.toLong(), TimeUnit.MILLISECONDS)
   }
 }