Remove persistent_shell experiment suite from android-pie-arm64-rel

Experiment is over as feature was turned on in:
https://chromium-review.googlesource.com/c/chromium/src/+/3984446

Will wait to ensure that feature turned on is stable before
landing this CL.

Bug: 1239300
Change-Id: I9944d2dc10f39cd6c11aeb7d18266fe92d3340cc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3983594
Reviewed-by: Haiyang Pan <[email protected]>
Commit-Queue: Benjamin Joyce (Ben) <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1065604}
diff --git a/testing/buildbot/test_suite_exceptions.pyl b/testing/buildbot/test_suite_exceptions.pyl
index e327e7d..e1cca45 100644
--- a/testing/buildbot/test_suite_exceptions.pyl
+++ b/testing/buildbot/test_suite_exceptions.pyl
@@ -1251,6 +1251,9 @@
   },
   # TODO(crbug/1239300): Remove when experiment is done.
   'chrome_public_persistent_shell_test_apk': {
+    'remove_from': [
+      'android-pie-arm64-rel', # crbug/1239300. Experiment is done on this bot.
+    ],
     'modifications': {
       'android-nougat-x86-rel': {
         'args': [