Revert "[iOS] Reenable PassKitEGTest/testPassKitDownload"

This reverts commit c0c1dee7.

Reason for revert: Continues to crash on iOS 12.4 iPhone X when built with the iOS 14 SDK.

Original change's description:
> [iOS] Reenable PassKitEGTest/testPassKitDownload
> 
> The test was disabled due to flakiness, but it looks fine on try bots.
> 
> Bug: 1109131
> Change-Id: I9f113a468e5b415344b70510918ef07e791bfd75
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2354947
> Commit-Queue: Zhaoyang Li <zhaoyangli@chromium.org>
> Reviewed-by: Eugene But <eugenebut@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#798285}

TBR=eugenebut@chromium.org,zhaoyangli@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1109131
Change-Id: I3adf02d233cbf055858ca6dd37fe8c0bef697903
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2361845Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Commit-Queue: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799087}

ios/chrome/browser/ui/download/pass_kit_egtest.mm

@@ -122,7 +122,9 @@ std::unique_ptr<net::test_server::HttpResponse> GetResponse(
 
 // Tests that Chrome PassKit dialog is shown for sucessfully downloaded pkpass
 // file.
-- (void)testPassKitDownload {
+//
+// Flaky https://crbug.com/1109131.
+- (void)DISABLED_testPassKitDownload {
   if ([ChromeEarlGrey isIPadIdiom]) {
     EARL_GREY_TEST_SKIPPED(@"Wallet app is not supported on iPads.");
   }