Revert of Convert Site Isolation Win bot to --isolate-extensions [2nd attempt].

testing/buildbot/filters/BUILD.gn

-# Copyright 2016 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-# This BUILD.gn file groups together filter files for particular test suites -
-# for example filters applicable to content_browsertests are exposed as
-# the //testing/buildbot/filters:content_browsertests target.
-
-# Note that all filter files (for a given test suite) are unconditionally listed
-# together, even if some filter files are applicable only to some platforms.
-# This should help avoid unpleasant surprises when a bot config is switched in
-# testing/buildbot/chromium.fyi.json without corresponding dependency changes
-# here - see https://crbug.com/661447.
-
-# To refresh, a command similar to the one below might be run in bash:
-# $ for i in $(ls -1 testing/buildbot/filters/*.browser_tests.*filter ); \
-#   do echo "    \"//$i\","; done | sort
-
-source_set("browser_tests") {
-  testonly = true
-
-  data = [
-    "//testing/buildbot/filters/browser-side-navigation.linux.browser_tests.filter",
-    "//testing/buildbot/filters/isolate-extensions.browser_tests.filter",
-    "//testing/buildbot/filters/mash.browser_tests.filter",
-    "//testing/buildbot/filters/mojo.fyi.browser_tests.filter",
-    "//testing/buildbot/filters/site-per-process.browser_tests.filter",
-  ]
-}
-
-source_set("content_browsertests") {
-  testonly = true
-
-  data = [
-    "//testing/buildbot/filters/browser-side-navigation.linux.content_browsertests.filter",
-    "//testing/buildbot/filters/cast-linux.content_browsertests.filter",
-    "//testing/buildbot/filters/isolate-extensions.content_browsertests.filter",
-    "//testing/buildbot/filters/site-per-process.content_browsertests.filter",
-  ]
-}