Do not process messages until new messages are feeding

There may be race condition as the initial messages may have been
processed before the TestableLooper is initialized.

Bug: 176119417
Test: atest TeleServiceTests:com.android.phone.RcsProvisioningMonitorTest
Change-Id: I7dead5b72fb465e7c32964e6f0a42b1efb1a7765
diff --git a/tests/src/com/android/phone/RcsProvisioningMonitorTest.java b/tests/src/com/android/phone/RcsProvisioningMonitorTest.java
index 7ef9768..e63e558 100644
--- a/tests/src/com/android/phone/RcsProvisioningMonitorTest.java
+++ b/tests/src/com/android/phone/RcsProvisioningMonitorTest.java
@@ -452,7 +452,6 @@
         } catch (Exception e) {
             logd("Unable to create looper from handler.");
         }
-        processAllMessages();
     }
 
     private void broadcastCarrierConfigChange(int subId) {