Reland "Enabled FeedbackKit V2 without SSOService object."

This is a reland of af7f86c1
http://crrev/i/598602 disabled or fixed the egtests that failed.

Original change's description:
> Enabled FeedbackKit V2 without SSOService object.
>
> This replaces http://crrev/c/986713 (which I botched during rebasing).
>
> Bug: 814587
> Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
> Change-Id: I214ea18fd70c218ad44718b29b6e9c8ed35ee1bc
> Reviewed-on: https://chromium-review.googlesource.com/987539
> Commit-Queue: Peter Lee <pkl@chromium.org>
> Commit-Queue: Sergio Collazos <sczs@chromium.org>
> Reviewed-by: Sergio Collazos <sczs@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#547116}

Bug: 814587
Change-Id: I602728c927f265937ed10c4c976ace2aeca1b000
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Reviewed-on: https://chromium-review.googlesource.com/988453Reviewed-by: Sergio Collazos <sczs@chromium.org>
Commit-Queue: Peter Lee <pkl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547301}

ios/chrome/browser/ui/user_feedback_features.cc

@@ -5,7 +5,7 @@
 #include "ios/chrome/browser/ui/user_feedback_features.h"
 
 const base::Feature kFeedbackKitV2{"FeedbackKitV2",
-                                   base::FEATURE_DISABLED_BY_DEFAULT};
+                                   base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kFeedbackKitV2WithSSOService{
     "FeedbackKitV2WithSSOService", base::FEATURE_DISABLED_BY_DEFAULT};