[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}

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

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