For #17906 - Allow screenshots for private home screenshot test

app/src/androidTest/java/org/mozilla/fenix/screenshots/DefaultHomeScreenTest.kt

@@ -44,10 +44,14 @@ class DefaultHomeScreenTest : ScreenshotTest() {
             SystemClock.sleep(TestAssetHelper.waitingTimeShort)
             Screengrab.screenshot("HomeScreenRobot_home-screen")
         }.openThreeDotMenu {
-        }.openSettings { }
+        }.openSettings {
+        }.openPrivateBrowsingSubMenu {
+            clickPrivateModeScreenshotsSwitch()
+        }
         // To get private screenshot,
         // dismiss onboarding going to settings and back
         mDevice.pressBack()
+        mDevice.pressBack()
         homeScreen {
             togglePrivateBrowsingModeOnOff()
             Screengrab.screenshot("HomeScreenRobot_private-browsing-menu")

app/src/androidTest/java/org/mozilla/fenix/ui/robots/SettingsSubMenuPrivateBrowsingRobot.kt

@@ -46,6 +46,8 @@ class SettingsSubMenuPrivateBrowsingRobot {
 
     fun verifyPrivateBrowsingShortcutIcon() = assertPrivateBrowsingShortcutIcon()
 
+    fun clickPrivateModeScreenshotsSwitch() = screenshotsInPrivateModeSwitch().click()
+
     fun clickOpenLinksInPrivateTabSwitch() = openLinksInPrivateTabSwitch().click()
 
     fun addPrivateShortcutToHomescreen() {
@@ -92,6 +94,9 @@ private fun assertNavigationToolBarHeader() {
 private fun openLinksInPrivateTabSwitch() =
     onView(withText("Open links in a private tab"))
 
+private fun screenshotsInPrivateModeSwitch() =
+    onView(withText("Allow screenshots in private browsing"))
+
 private fun addPrivateBrowsingShortcutButton() = onView(withText("Add private browsing shortcut"))
 
 private fun goBackButton() = onView(withContentDescription("Navigate up"))