Remove redundant --wait-for-staged-ready flag

Staged install by default waits for staged session to become ready. So
this flag isn't necessary.

Bug: 162958790
Test: atest StagedInstallInternalTest
Change-Id: I43ea49ff2576691556587df6cfd2d442c39e5284
diff --git a/tests/util/com/android/tests/util/ModuleTestUtils.java b/tests/util/com/android/tests/util/ModuleTestUtils.java
index 03dea36..9f093b4 100644
--- a/tests/util/com/android/tests/util/ModuleTestUtils.java
+++ b/tests/util/com/android/tests/util/ModuleTestUtils.java
@@ -41,7 +41,6 @@
 import java.util.stream.Stream;
 
 public class ModuleTestUtils {
-    private static final String SHIM = "com.android.apex.cts.shim";
     private static final String APEX_INFO_EXTRACT_REGEX =
             ".*package:\\sname='(\\S+)\\'\\sversionCode='(\\d+)'\\s.*";
 
@@ -121,8 +120,7 @@
      * Installs packages using staged install flow and waits for pre-reboot verification to complete
      */
     public String installStagedPackage(File pkg) throws Exception {
-        return mTest.getDevice().installPackage(pkg, false,
-                "--staged", "--wait-for-staged-ready");
+        return mTest.getDevice().installPackage(pkg, false, "--staged");
     }
 
     private String runCmd(String cmd) {