Revert "Set window_manager: False on Linux Tests bot."
Revert "Set window_manager: False on Linux Tests bot."

This reverts commit 2aada149f78bddf65a6462ce2e0194f323a16db9.

The reverted commit was an experimental change to try to reduce cycle times on
the Linux Tests bot on chromium.linux by making it behave more like the faster
Linux Aura bot. The change was unsuccessful: browser_tests remained flaky and
kept the same high cycle time due to retries, and ui_unittests and
base_unittests may have become worse.

TBR=cmp@chromium.org,dpranke@chromium.org
BUG=319075

Review URL: https://codereview.chromium.org/72813003

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@235158 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build