[iOS] Update url used for network connectivity check

The page at the previous url was much more complicated than necessary
for a network check so it could more easily fail for other non-network
related issues.

Bug: None
Change-Id: I9f79cb9f948b090c065cf6b9f9331217e65b380d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2311043
Commit-Queue: Mike Dougherty <michaeldo@chromium.org>
Commit-Queue: Rohit Rao <rohitrao@chromium.org>
Auto-Submit: Mike Dougherty <michaeldo@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790641}

ios/chrome/test/earl_grey/device_check_egtest.mm

@@ -19,8 +19,9 @@
 
 // Verifies Internet connectivity by navigating to browsingtest.appspot.com.
 - (void)testNetworkConnection {
-  [ChromeEarlGrey loadURL:GURL("http://browsingtest.appspot.com")];
-  [ChromeEarlGrey waitForWebStateContainingText:"Window1"];
+  [ChromeEarlGrey
+      loadURL:GURL("http://browsingtest.appspot.com/googleLogoPage.html")];
+  [ChromeEarlGrey waitForWebStateContainingText:"some text"];
 }
 
 @end