Revert "Enable AppService InstanceRegistry feature."

This reverts commit 162137c6.

Reason for revert: crbug.com/1036648: This CL triggers heap-use-after-free in ASAN (although the root cause lies elsewhere, maybe inactive code). Reverting to denoise system.

Original change's description:
> Enable AppService InstanceRegistry feature.
>
> BUG=1011235
>
> Change-Id: Icb262a58b4464d7963acb0b22a9d30ce7b070060
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1972738
> Commit-Queue: Nancy Wang <nancylingwang@chromium.org>
> Reviewed-by: Dominick Ng <dominickn@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#726576}

TBR=dominickn@chromium.org,nancylingwang@chromium.org

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

Bug: 1036648, 1011235
Change-Id: Ib942d2a4f72e24871adea66626dc95b78a8f06c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1979850
Commit-Queue: Samuel Huang <huangs@chromium.org>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727062}

chrome/common/chrome_features.cc

@@ -64,7 +64,7 @@ const base::Feature kAppNotificationStatusMessaging{
 #if !defined(OS_ANDROID)
 // App Service related flags. See chrome/services/app_service/README.md.
 const base::Feature kAppServiceInstanceRegistry{
-    "AppServiceInstanceRegistry", base::FEATURE_ENABLED_BY_DEFAULT};
+    "AppServiceInstanceRegistry", base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kAppServiceIntentHandling{
     "AppServiceIntentHandling", base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kAppServiceShelf{"AppServiceShelf",