Mark PaintTouchActionRects as status=test due to stylus/touch regression

This patch switches PaintTouchActionRects to status=test while the
root-cause of https://crbug.com/903480 is investigated. This will
turn the feature off for end-users and performance tests, though it is
still on for layout tests and content shell.

Bug: 903480
Change-Id: Iff6695cd6140c7caf29819a856a7b894fd4d6733
Reviewed-on: https://chromium-review.googlesource.com/c/1330070
Commit-Queue: Philip Rogers <pdr@chromium.org>
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606963}

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -899,7 +899,7 @@
     // Compute touch action rects in paint instead of ScrollingCoordinator.
     {
       name: "PaintTouchActionRects",
-      status: "stable",
+      status: "test",
     },
     // PaintTracking enables the Largest Text Paint metric, Last Text Paint
     // metric, Largest Image Paint metric and Last Image Paint metric.