Turn on persistent_shell for arm64 chrome_public_test_apk.

Turn on persistent_shell for android-pie-arm64-rel for
chrome_public_test_apk. Test suite has been running in
experiment for a few weeks in chrome_public_persistent_shell_test_apk.

It shows a decrease in shard runtime from: 237m 50s to 214m 46s.

Out of 86 runs:
PasswordSavingIntegrationTest#testUpdatingPassword:
flaked 3 and 4 times with persistent shell and without persistent_shell respectively.

Various AutofillAssistant tests timed out 4 and 7 times on tests with persistent shell and without persistent_shell respectively:
crbug/1263730, crbug/1367093, crbug/1270760, crbug/1263730,
crbug/1263727, crbug/1163913, crbug/1154682.

testShow_SingleAsHomepage_ResetScrollPosition__Instant_NoReturn:
failed once on chrome_public_test_apk without persistent_shell failing, but is flaky crbug/1294402

testSigninButtonDefaultAccount: test failed once on persistent shell without failing on chrome_public_test_apk. Seems to be flakey  elsewhere: crbug/1378080

Bug: 1021686,1239300
Change-Id: Ic1e44044343cc1ae25cae44254f51b1d15170905
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3984446
Reviewed-by: Nate Fischer <[email protected]>
Reviewed-by: Haiyang Pan <[email protected]>
Reviewed-by: Ben Pastene <[email protected]>
Commit-Queue: Benjamin Joyce (Ben) <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1063989}
diff --git a/testing/buildbot/test_suite_exceptions.pyl b/testing/buildbot/test_suite_exceptions.pyl
index c51c170..db703e1a 100644
--- a/testing/buildbot/test_suite_exceptions.pyl
+++ b/testing/buildbot/test_suite_exceptions.pyl
@@ -1338,6 +1338,7 @@
       'android-pie-arm64-rel': {
         'args': [
           '--test-launcher-filter-file=../../testing/buildbot/filters/android.pie_arm64_rel.chrome_public_test_apk.filter', # https://crbug.com/1010211
+          '--use-persistent-shell',
         ],
         'ci_only': True, # https://crbug.com/1233700
       },