Revert "[metrics] Always enable background thread"

This reverts commit 6660e3bd463535ea6aefebc3288ac3f17fbd99fd.

Bug: 170149255

Reason for revert: Test ThreadLifecycleCallbackJava flakey.

Change-Id: Ib118654c414c27bd71d7ad3e19e1fab2d06347c7
diff --git a/test/911-get-stack-trace/src/art/PrintThread.java b/test/911-get-stack-trace/src/art/PrintThread.java
index f843cc3..94f3a33 100644
--- a/test/911-get-stack-trace/src/art/PrintThread.java
+++ b/test/911-get-stack-trace/src/art/PrintThread.java
@@ -42,8 +42,7 @@
   // may not exist depending on the environment.
   public final static String IGNORE_THREAD_NAME_REGEX =
       "Binder:|RenderThread|hwuiTask|Jit thread pool worker|Instr:|JDWP|Profile Saver|main|" +
-      "queued-work-looper|InstrumentationConnectionThread|intel_svc_streamer_thread|" +
-      "ForkJoinPool|Metrics Background Reporting Thread";
+      "queued-work-looper|InstrumentationConnectionThread|intel_svc_streamer_thread|ForkJoinPool";
   public final static Matcher IGNORE_THREADS =
       Pattern.compile(IGNORE_THREAD_NAME_REGEX).matcher("");