[WPT import] Temporarily disable orphaned baseline removal

Importer is now trying to remove baselines for test with query strings
in the names, e.g.
https://chromium-review.googlesource.com/c/chromium/src/+/874798/1

We were lucky as the CL above didn't cause any actual damage (the
rebaseline step added all removed baselines back), but it's too risky.
Temporarily disable this feature before I fix it.

TBR=qyearsley

Bug: 800570
Change-Id: Id1f4b484badb7e2a651dbf6e37ccffe3d25fe7eb
Reviewed-on: https://chromium-review.googlesource.com/874726Reviewed-by: Robert Ma <robertma@chromium.org>
Commit-Queue: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#530388}

third_party/WebKit/Tools/Scripts/webkitpy/w3c/test_importer.py

@@ -133,7 +133,8 @@ class TestImporter(object):
 
         self._generate_manifest()
 
-        self._delete_orphaned_baselines()
+        # TODO(crbug.com/800570 robertma): Re-enable it once we fix the bug.
+        # self._delete_orphaned_baselines()
 
         # TODO(qyearsley): Consider running the imported tests with
         # `run-webkit-tests --reset-results external/wpt` to get some baselines