[ios] Fix FirstRunTestCase failure by disabling Location Feature

With the location permissions client-side driven experiment,
test runs were being bucketed in the experiment and the First Run
modal was sometimes showing, leading to failures. Thus,
kLocationPermissionsPrompt should be disabled.

TBR=marq@chromium.org

Bug: 1148054
Change-Id: I33dee1282e77831f37e561a76ad1cff790710e4c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2533321Reviewed-by: Chris Lu <thegreenfrog@chromium.org>
Commit-Queue: Chris Lu <thegreenfrog@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826642}

ios/chrome/browser/ui/first_run/BUILD.gn

@@ -131,6 +131,7 @@ source_set("eg2_tests") {
     "//base/test:test_support",
     "//ios/chrome/app/strings:ios_chromium_strings_grit",
     "//ios/chrome/app/strings:ios_strings_grit",
+    "//ios/chrome/browser/ui:feature_flags",
     "//ios/chrome/browser/ui/authentication:eg_test_support+eg2",
     "//ios/chrome/browser/ui/authentication/signin:constants",
     "//ios/chrome/test/earl_grey:eg_test_support+eg2",

ios/chrome/browser/ui/first_run/first_run_egtest.mm

@@ -9,6 +9,7 @@
 #import "ios/chrome/browser/ui/authentication/signin_earl_grey_ui.h"
 #import "ios/chrome/browser/ui/first_run/first_run_app_interface.h"
 #import "ios/chrome/browser/ui/first_run/first_run_constants.h"
+#include "ios/chrome/browser/ui/ui_feature_flags.h"
 #include "ios/chrome/grit/ios_chromium_strings.h"
 #include "ios/chrome/grit/ios_strings.h"
 #import "ios/chrome/test/earl_grey/chrome_matchers.h"
@@ -55,6 +56,12 @@ id<GREYMatcher> SkipSigninButton() {
   [FirstRunAppInterface resetUMACollectionEnabledByDefault];
 }
 
+- (AppLaunchConfiguration)appConfigurationForTestCase {
+  AppLaunchConfiguration config;
+  config.features_disabled.push_back(kLocationPermissionsPrompt);
+  return config;
+}
+
 // Navigates to the terms of service and back.
 - (void)testTermsAndConditions {
   [FirstRunAppInterface showFirstRunUI];