FIX: Integration tests CI instability on Integration_CanSendAndReceiveEvents (#1693)

* Set background settings to ignore focus

This makes the devices adding during tests to be enabled regardless
of the standalone player application focus.

* Update CHANGELOG

Author: jfreire-unity

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -15,6 +15,7 @@ however, it has to be formatted properly to pass verification tests.
 
 ### Fixed
 - Fixed UI clicks not registering when OS provides multiple input sources for the same event, e.g. on Samsung Dex (case ISX-1416, ISXB-342).
+- Fixed unstable integration test `Integration_CanSendAndReceiveEvents` by ignoring application focus on integration tests. (case ISX-1381)
 
 ## [1.6.1] - 2023-05-26
 

Packages/com.unity.inputsystem/Tests/IntegrationTests/IntegrationTests.cs

@@ -68,6 +68,22 @@ public static void PreserveMethods()
         var dummy = new System.ComponentModel.StringConverter();
     }
 
+    [SetUp]
+    public virtual void Setup()
+    {
+        // The standalone player can go out of focus when running tests. This makes the devices added during tests set
+        // as disabled. Which in turn makes the InputSystem update not process input state changes for devices.
+        // By ignoring focus, we can protect ourselves against this and always update the device state in the standalone
+        // test players
+        InputSystem.settings.backgroundBehavior = InputSettings.BackgroundBehavior.IgnoreFocus;
+    }
+
+    [TearDown]
+    public virtual void TearDown()
+    {
+        InputSystem.settings.backgroundBehavior = default;
+    }
+
     [Test]
     [Category("Integration")]
     public void Integration_CanSendAndReceiveEvents()