Set package name.

The system expects an actual package name in the ApplicationInfo object
so make sure to set it in the test object.

Bug: 258472566
Test: atest AppButtonsTest
Change-Id: I3bee07a6a395c9962af57f934cf3ca86eb60354a

tests/spa_unit/src/com/android/settings/spa/app/appinfo/AppButtonsTest.kt

@@ -125,7 +125,10 @@ class AppButtonsTest {
     private companion object {
         const val PACKAGE_NAME = "package.name"
         val PACKAGE_INFO = PackageInfo().apply {
-            applicationInfo = ApplicationInfo()
+            applicationInfo = ApplicationInfo().apply {
+                packageName = PACKAGE_NAME
+            }
+            packageName = PACKAGE_NAME
         }
     }
 }