Toggle flag to make automation_egtest record exception in -setUp()

Current autofill automation framework attempts 5 times for a test to
deal with flaky issue. To achieve this, XCTestCase's
recordFailureWithDescription:inFile:atLine:expected: method is disabled
before 5th attempt with a flag. The flag is false by default and this
makes assertion failure won't fail the test during -setUp() period.
This change toggle the flag to true before -setUp() so assertions will
work as expected in -setUp().

Bug: 1006452
Change-Id: I6d902e23e7d74dcac9f3ee279a1bd65c00f468db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1817296Reviewed-by: Eric Noyau <noyau@chromium.org>
Reviewed-by: Yun Liu <yliuyliu@google.com>
Commit-Queue: Zhaoyang Li <zhaoyangli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702092}

ios/chrome/browser/autofill/automation/automation_egtest.mm

@@ -196,6 +196,8 @@ static const int kRecipeRetryLimit = 5;
 }
 
 - (void)setUp {
+  self->shouldRecordException = true;
+
   [super setUp];
 
   const base::FilePath recipePath = [[self class] recipePath];