Remove Thread.sleep()

Install#commit ensures a staged session is ready before the function
returns. So we don't need to sleep to wait for disk IO to complete.

Bug: 143211397
Test: atest StagedRollbackTest
Change-Id: Ic4b53dc5aaef7a22d7d64c14ee4f77bee84c26b1
diff --git a/tests/RollbackTest/RollbackTest/src/com/android/tests/rollback/StagedRollbackTest.java b/tests/RollbackTest/RollbackTest/src/com/android/tests/rollback/StagedRollbackTest.java
index 82eef7f..8b01930 100644
--- a/tests/RollbackTest/RollbackTest/src/com/android/tests/rollback/StagedRollbackTest.java
+++ b/tests/RollbackTest/RollbackTest/src/com/android/tests/rollback/StagedRollbackTest.java
@@ -237,8 +237,6 @@
                 Integer.toString(120000), false);
         // Simulate re-installation of new NetworkStack with rollbacks enabled
         installNetworkStackPackage();
-        // Sleep to allow writes to disk before reboot
-        Thread.sleep(TimeUnit.SECONDS.toMillis(5));
     }
 
     @Test