Make sure storages ready before testing AdoptableHostTest

This is timing issue.
The setUp() in AdoptableHostTest would set persist.sys.virtual_disk.
And that will cause StorageManager to "reset" all storages.

If try to run the testcase immediately after setUp(), it will cause testcase
failed because storages are not mounted.

For example, testPrimaryOnSameVolume failed because the primary storage
is not mounted.

Test: atest AdoptableHostTest
Bug: 160561499

Change-Id: Ib98f773f4413e54b34d88b974d4750937bbc7765
diff --git a/hostsidetests/appsecurity/src/android/appsecurity/cts/AdoptableHostTest.java b/hostsidetests/appsecurity/src/android/appsecurity/cts/AdoptableHostTest.java
index 927f9f5..dd47dd6 100644
--- a/hostsidetests/appsecurity/src/android/appsecurity/cts/AdoptableHostTest.java
+++ b/hostsidetests/appsecurity/src/android/appsecurity/cts/AdoptableHostTest.java
@@ -82,6 +82,8 @@
                 hasVirtualDisk = result.startsWith("disk:");
             }
             assertTrue("Virtual disk is not ready: " + result, hasVirtualDisk);
+
+            waitForVolumeReady();
         }
     }