Revert "Disable Feed v2 build flag on stable channel"

This reverts commit 0048fa4a.

Reason for revert: Previous CL was for merging to stable branch only

Original change's description:
> Disable Feed v2 build flag on stable channel
> 
> Bug: 1129504
> Change-Id: Icb74a2b914c65ba2cfda14409f0d7a7642d132f4
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2417049
> Auto-Submit: Carlos Knippschild <carlosk@chromium.org>
> Reviewed-by: Justin DeWitt <dewittj@chromium.org>
> Commit-Queue: Justin DeWitt <dewittj@chromium.org>
> Commit-Queue: Carlos Knippschild <carlosk@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#808013}

TBR=dewittj@chromium.org,carlosk@chromium.org

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

Bug: 1129504
Change-Id: I119b1221f95d79901af4ae8d6a0fc1259aaf0b26
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2422298Reviewed-by: Dan H <harringtond@chromium.org>
Reviewed-by: Carlos Knippschild <carlosk@chromium.org>
Commit-Queue: Dan H <harringtond@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808947}

components/feed/features.gni

@@ -2,9 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//chrome/android/channel.gni")
-
 declare_args() {
   enable_feed_in_chrome = is_android
-  enable_feed_v2 = is_android && android_channel != "stable"
+  enable_feed_v2 = is_android
 }