Revert "PM: Enable service worker relationships in graph."

This reverts commit 5fce665c.

Reason for revert: https://crbug.com/1168113

Original change's description:
> PM: Enable service worker relationships in graph.
>
> Bug: 1143281
> Change-Id: Ibc54e560a2a2a5f38c6ef48c7352c40c1b82109c
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2636273
> Commit-Queue: Sigurður Ásgeirsson <siggi@chromium.org>
> Commit-Queue: Patrick Monette <pmonette@chromium.org>
> Reviewed-by: Patrick Monette <pmonette@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#844550}

TBR=pmonette@chromium.org,siggi@chromium.org,chromium-scoped@luci-project-accounts.iam.gserviceaccount.com

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

Bug: 1143281,1168113
Change-Id: Ie84eef7095d735bd4e8b4e0d7fb097b20419a0b8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2637266Reviewed-by: Sigurður Ásgeirsson <siggi@chromium.org>
Commit-Queue: Sigurður Ásgeirsson <siggi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844933}

components/performance_manager/features.cc

@@ -48,7 +48,16 @@ TabLoadingFrameNavigationThrottlesParams::GetParams() {
 }
 
 const base::Feature kServiceWorkerRelationshipsInGraph{
-    "ServiceWorkerRelationshipsInGraph", base::FEATURE_ENABLED_BY_DEFAULT};
+  "ServiceWorkerRelationshipsInGraph",
+#if DCHECK_IS_ON()
+      // Enable service worker relationships by default under debug builds in
+      // order to get DCHECK failures from Alabatross.
+      // TODO(https://crbug.com/1143281): Revert once there's sufficient data.
+      base::FEATURE_ENABLED_BY_DEFAULT
+#else
+      base::FEATURE_DISABLED_BY_DEFAULT
+#endif
+};
 
 }  // namespace features
 }  // namespace performance_manager