Adjust tests on android-pie-arm64-rel.

Enable the following as they are consistently green:
* chrome_public_smoke_test
* weblayer_unittests
* webview_ui_test_app_test_apk

Run chrome_public_test_apk at 100% experimentally. According to the bot
usage (http://shortn/_hEy8np3sYC) and swarming tasks status
(http://shortn/_7gxoNS82Qr), the test pool might experience some pending
time. Will keep an eye on it and revert if it causes any issue.
Also disabled 4 flaky tests. See the filter file for details.

Bug: 1111436, 1165449, 1165456, 1165459
Change-Id: Ic1e2a1e431639f8f0ea882f2a412281166222abf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2622006Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
Reviewed-by: Ben Pastene <bpastene@chromium.org>
Commit-Queue: Haiyang Pan <hypan@google.com>
Cr-Commit-Position: refs/heads/master@{#842816}

testing/buildbot/chromium.android.json

@@ -41673,7 +41673,6 @@
           "--gs-results-bucket=chromium-result-details",
           "--recover-devices"
         ],
-        "experiment_percentage": 100,
         "merge": {
           "args": [
             "--bucket",
@@ -41726,7 +41725,7 @@
           "--git-revision=${got_revision}",
           "--test-launcher-filter-file=../../testing/buildbot/filters/android.pie_arm64_rel.chrome_public_test_apk.filter"
         ],
-        "experiment_percentage": 50,
+        "experiment_percentage": 100,
         "merge": {
           "args": [
             "--bucket",
@@ -42084,7 +42083,6 @@
           "--gs-results-bucket=chromium-result-details",
           "--recover-devices"
         ],
-        "experiment_percentage": 100,
         "merge": {
           "args": [
             "--bucket",
@@ -42242,7 +42240,6 @@
           "--gs-results-bucket=chromium-result-details",
           "--recover-devices"
         ],
-        "experiment_percentage": 100,
         "merge": {
           "args": [
             "--bucket",

testing/buildbot/filters/android.pie_arm64_rel.chrome_public_test_apk.filter

@@ -83,3 +83,13 @@
 
 # crbug.com/1128665
 -org.chromium.chrome.browser.download.DownloadTest.testDuplicateHttpPostDownload_Cancel__UseDownloadOfflineContentProviderEnabled
+
+# crbug.com/1165449
+-org.chromium.chrome.browser.firstrun.TosAndUmaFirstRunFragmentWithEnterpriseSupportTest.testAcceptTosWithoutCrashUpload
+
+# crbug.com/1165456
+-org.chromium.chrome.browser.paint_preview.StartupPaintPreviewTest.testRemoveOnActionbarClick
+-org.chromium.chrome.browser.paint_preview.StartupPaintPreviewTest.testSnackbarShow
+
+# crbug.com/1165459
+-org.chromium.chrome.browser.share.long_screenshots.LongScreenshotsEntryTest.testCaptured

testing/buildbot/test_suite_exceptions.pyl

@@ -729,12 +729,6 @@
     'remove_from': [
       'android-code-coverage-native', # https://crbug.com/1018780
     ],
-    # TODO(crbug.com/1111436): Remove experimental when it works fine.
-    'modifications': {
-      'android-pie-arm64-rel': {
-          'experiment_percentage': 100,
-      },
-    },
   },
   'chrome_public_test_apk': {
     'remove_from': [
@@ -795,7 +789,7 @@
           '--test-launcher-filter-file=../../testing/buildbot/filters/android.pie_arm64_rel.chrome_public_test_apk.filter', # https://crbug.com/1010211
         ],
         # TODO(crbug.com/1111436): Remove experimental when it works fine.
-        'experiment_percentage': 50,
+        'experiment_percentage': 100,
       },
       'android-pie-x86-rel': {
         'args': [
@@ -2935,14 +2929,6 @@
       },
     },
   },
-  # TODO(crbug.com/1111436): Remove this once it works fine.
-  'weblayer_unittests': {
-    'modifications': {
-      'android-pie-arm64-rel': {
-        'experiment_percentage': 100,
-      },
-    },
-  },
   'webview_cts_tests': {
     'modifications': {
       'android-pie-arm64-rel': {
@@ -2993,14 +2979,6 @@
       },
     },
   },
-  # TODO(crbug.com/1111436): Remove this once it works fine.
-  'webview_ui_test_app_test_apk': {
-    'modifications': {
-      'android-pie-arm64-rel': {
-        'experiment_percentage': 100,
-      },
-    },
-  },
   'xr_browser_tests': {
     'remove_from': [
       # This exception probably needs to stay due to lack of capacity