Reenable updating-the-finished-state.html test

Source of the flakiness fixed in
https://chromium-review.googlesource.com/c/chromium/src/+/2621924

These tests were not actually able to run on the compositor since the
keyframes where empty and thus not affecting a property that could be
composited. The flakes were appearing on both the virtual and base test
suites; however, only the virtual version was disabled.

This patch re-enables the test in the virtual test suite.

Bug: 1139023
Change-Id: I4811b7fa0850cb7346448e008f4652eda547f372
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2622340Reviewed-by: Xida Chen <xidachen@chromium.org>
Commit-Queue: Kevin Ellis <kevers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842635}

third_party/blink/web_tests/TestExpectations

@@ -5704,7 +5704,6 @@ crbug.com/1123116 external/wpt/feature-policy/reporting/xr-reporting.https.html
 crbug.com/1159445 [ Mac ] paint/invalidation/repaint-overlay/layers-overlay.html [ Failure ]
 
 crbug.com/1140329 http/tests/devtools/network/network-filter-service-worker.js [ Pass Timeout Failure ]
-crbug.com/1140329 virtual/threaded/external/wpt/web-animations/timing-model/animations/updating-the-finished-state.html [ Pass Failure Timeout ]
 
 #Sheriff 2020-10-21
 crbug.com/1141206 scrollbars/overflow-scrollbar-combinations.html [ Pass Failure ]