Revert "PM: Enable service worker relationships by default."

This reverts commit 0dadfa21.

Reason for revert: Top crasher on Canary.

Original change's description:
> PM: Enable service worker relationships by default.
>
> Bug: 1143281
> Change-Id: I5107ca4d324248456470f5880429d10760d77076
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2557223
> Reviewed-by: Patrick Monette <pmonette@chromium.org>
> Commit-Queue: Sigurður Ásgeirsson <siggi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#830661}

TBR=pmonette@chromium.org,siggi@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1152860, 1143281
Change-Id: Ie1e445d3da4185e65bfb8f895b6d63468b01be1b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2561538Reviewed-by: Sigurður Ásgeirsson <siggi@chromium.org>
Commit-Queue: Sigurður Ásgeirsson <siggi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#831161}

components/performance_manager/features.cc

@@ -47,7 +47,7 @@ TabLoadingFrameNavigationThrottlesParams::GetParams() {
 }
 
 const base::Feature kServiceWorkerRelationshipsInGraph{
-    "ServiceWorkerRelationshipsInGraph", base::FEATURE_ENABLED_BY_DEFAULT};
+    "ServiceWorkerRelationshipsInGraph", base::FEATURE_DISABLED_BY_DEFAULT};
 
 }  // namespace features
 }  // namespace performance_manager

components/performance_manager/worker_watcher_unittest.cc

@@ -1336,8 +1336,7 @@ void WorkerWatcherTest::TestFrameDestroyed(
     feature_list.InitAndEnableFeature(
         features::kServiceWorkerRelationshipsInGraph);
   } else {
-    feature_list.InitAndDisableFeature(
-        features::kServiceWorkerRelationshipsInGraph);
+    feature_list.Init();
   }
 
   int render_process_id = process_node_source()->CreateProcessNode();