Revert "[Sharesheet] Turn on flags to enable sharesheet by default."

This reverts commit 2374eacf.

Reason for revert: Punting sharesheet to 89 so flags need to be disabled.

Original change's description:
> [Sharesheet] Turn on flags to enable sharesheet by default.
>
> This CL turns on the kIntentHandlingSharing and kSharesheet flags to
> enable sharesheet feature by default.
>
> BUG=1097623
>
> Change-Id: Idff4e37934fb730b7f83b86206d555a8c049f12e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2460206
> Commit-Queue: Maggie Cai <mxcai@chromium.org>
> Reviewed-by: Dominick Ng <dominickn@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#816071}

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

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

Bug: 1097623
Change-Id: I4d4914ad4ec363c2a63fdaaf7c55163dd1205f99
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2501161Reviewed-by: Melissa Zhang <melzhang@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Maggie Cai <mxcai@chromium.org>
Commit-Queue: Melissa Zhang <melzhang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821103}

chrome/common/chrome_features.cc

@@ -498,7 +498,7 @@ const base::Feature kInstallableAmbientBadgeInfoBar{
 #if !defined(OS_ANDROID)
 // Support sharing in Chrome OS intent handling.
 const base::Feature kIntentHandlingSharing{"IntentHandlingSharing",
-                                           base::FEATURE_ENABLED_BY_DEFAULT};
+                                           base::FEATURE_DISABLED_BY_DEFAULT};
 // Allow user to have preference for PWA in the intent picker.
 const base::Feature kIntentPickerPWAPersistence{
     "IntentPickerPWAPersistence", base::FEATURE_DISABLED_BY_DEFAULT};
@@ -708,7 +708,8 @@ const base::Feature kSecurityKeyAttestationPrompt{
     "SecurityKeyAttestationPrompt", base::FEATURE_ENABLED_BY_DEFAULT};
 
 #if defined(OS_CHROMEOS)
-const base::Feature kSharesheet{"Sharesheet", base::FEATURE_ENABLED_BY_DEFAULT};
+const base::Feature kSharesheet{"Sharesheet",
+                                base::FEATURE_DISABLED_BY_DEFAULT};
 #endif
 
 #if defined(OS_MAC)