weblayer, skew tests: Add --replace-system-package command line argument

Adding this command line argument fixes an issue with tests running
on Android M x86 emulator builders. The issue is that the emulator
fails to reboot after disabling boot verification.

Bug: 1114563, 1165307
Change-Id: Iab36b6c2c2ec3766e259fc1cfaa4c25fdc4fbb7b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2631159Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Rakib Hasan <rmhasan@google.com>
Cr-Commit-Position: refs/heads/master@{#844163}

testing/buildbot/gn_isolate_map.pyl

@@ -1935,6 +1935,10 @@
     "type": "console_test_launcher",
   },
   "weblayer_instrumentation_test_versions_apk": {
+    "args":  [
+      "--replace-system-package",
+      "org.chromium.weblayer.shell,apks/WebLayerShellSystemWebView.apk"
+    ],
     "label": "//weblayer/browser/android/javatests:weblayer_instrumentation_test_versions_apk",
     "type": "console_test_launcher",
   },