Use instrumentation arg to prevent unnecessary delays in unit tests

Bug: 308792359
Flag: NA
Test: presubmits passing
Change-Id: Ib38db86057998fcf859a44fa190e6cc4d82263dd
diff --git a/tests/Launcher3Tests.xml b/tests/Launcher3Tests.xml
index 3fff622..0aed1e1 100644
--- a/tests/Launcher3Tests.xml
+++ b/tests/Launcher3Tests.xml
@@ -46,5 +46,6 @@
     <test class="com.android.tradefed.testtype.AndroidJUnitTest" >
         <option name="package" value="com.android.launcher3.tests" />
         <option name="runner" value="androidx.test.runner.AndroidJUnitRunner" />
+        <option name="instrumentation-arg" key="waitForActivitiesToComplete" value="false" />
     </test>
 </configuration>