Revert "Flip the AppServiceAsh feature default to enabled"

This reverts commit 1b08fa8e.

Reason for revert: suspect causing unit_tests failure on linux-chromeos-dbg.
https://ci.chromium.org/p/chromium/builders/ci/linux-chromeos-dbg/13673
deterministic failures:
ArcAppLauncherForDefaultAppTest.AppIconUpdated/0
ArcAppLauncherForDefaultAppTest.AppIconUpdated/1
...
E.g.
https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8906357365557383728/+/steps/unit_tests/0/logs/Deterministic_failure:_ArcAppLauncherForDefaultAppTest.AppIconUpdated__x2f_0__status_CRASH_/0
[ RUN      ] ArcAppLauncherForDefaultAppTest.AppIconUpdated/0
Received signal 11 <unknown> 000000000000
#9 0x7f40f3cfd40b base::ThreadCheckerImpl::CalledOnValidThread()
#10 0x5611fbac0319 arc::internal::ConnectionNotifier::RemoveObserver()
#11 0x5611f8ea55e9 arc::ConnectionHolder<>::RemoveObserver()
#12 0x5611ff697745 apps::ArcApps::~ArcApps()
#13 0x5611ff69786c apps::ArcApps::~ArcApps()
...
#22 0x7f40e9d8e740 KeyedServiceFactory::Disassociate()
#23 0x7f40e9d8e834 KeyedServiceFactory::ContextDestroyed()
#24 0x7f40de6a3503 BrowserContextKeyedServiceFactory::BrowserContextDestroyed()
#25 0x7f40de6a3677 BrowserContextKeyedServiceFactory::ContextDestroyed()
#26 0x7f40e9d8b145 DependencyManager::DestroyFactoriesInOrder()
#27 0x7f40e9d8b1f5 DependencyManager::PerformInterlockedTwoPhaseShutdown()
#28 0x5611fe3b3fc3 TestingProfile::~TestingProfile()
#29 0x5611fe3b43cc TestingProfile::~TestingProfile()
...

Original change's description:
> Flip the AppServiceAsh feature default to enabled
> 
> BUG=826982
> BUG=989789
> 
> Change-Id: I49bd3793bf9fcfc89726fd2f7df690421996e0fd
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1728411
> Reviewed-by: Dominick Ng <dominickn@chromium.org>
> Commit-Queue: Nigel Tao <nigeltao@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#683064}

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

Change-Id: Iec931954750b6a58d2274c6479507e99efd2467a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 826982, 989789
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1731091Reviewed-by: Takashi Sakamoto <tasak@google.com>
Commit-Queue: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/master@{#683108}

chrome/common/chrome_features.cc

@@ -67,7 +67,7 @@ const base::Feature kAppNotificationStatusMessaging{
 // as AppServiceAsh. Enabling any one of those client-specific feature flags
 // also implicitly enables AppServiceServer.
 const base::Feature kAppServiceAsh{"AppServiceAsh",
-                                   base::FEATURE_ENABLED_BY_DEFAULT};
+                                   base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kAppServiceServer{"AppServiceServer",
                                       base::FEATURE_ENABLED_BY_DEFAULT};
 #endif  // !defined(OS_ANDROID)