Update fieldtrial config for RenderDocument to skip early commits.

http://cl/338053345 is updating the experiment to include disabling
SkipEarlyCommitPendingForCrashedFrame and this change is needed
alongside it.

Bug: 1072817,1139104
Change-Id: Ie2c54557d85ba0fbbe1a494626602f6f8daaf583
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2486009
Commit-Queue: Fergal Daly <fergal@chromium.org>
Commit-Queue: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Auto-Submit: Fergal Daly <fergal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818940}

testing/variations/fieldtrial_testing_config.json

@@ -5899,6 +5899,9 @@
                     },
                     "enable_features": [
                         "RenderDocument"
+                    ],
+                    "disable_features": [
+                        "SkipEarlyCommitPendingForCrashedFrame"
                     ]
                 }
             ]