[Mfill Android] Enable keyboard accessory v1 by default

Since we launch the keyboard accessory in M74, set the feature to
enabled by default with M76 (to keep as kill switch).

With M77, drop it then - this is already reflected in the
flag-metdata.json.

Automatic password generation is already enabled and also targeted to
removed with M77.

Bug: 853794
Change-Id: Iaf0dfe51753445eb868c27d5401636d4f0b1c42d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1598821Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Commit-Queue: Friedrich [CET] <fhorschig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#657270}

components/password_manager/core/common/password_manager_features.cc

@@ -65,7 +65,7 @@ const base::Feature kPasswordImport = {"PasswordImport",
 
 // Adds password-related features to the keyboard accessory on mobile devices.
 const base::Feature kPasswordsKeyboardAccessory = {
-    "PasswordsKeyboardAccessory", base::FEATURE_DISABLED_BY_DEFAULT};
+    "PasswordsKeyboardAccessory", base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Deletes entries from local database on Mac which cannot be decrypted when
 // merging data with Sync.