[CrOS PhoneHub] Fix Phone Hub multi-device setup settings

A previous CL [1] removed the "Phone Hub notification badge" feature,
but accidentally forgot to update the size of the kPhoneHubSubFeatures
array. This caused an issue which would accidentally read past the array
and cause incorrect FeatureStates to be provided.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/2462225

Bug: 1106937
Change-Id: Iabe0d5adceb321f5998989e5ba4524b63f477476
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2493220
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Regan Hsu <hsuregan@chromium.org>
Auto-Submit: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Regan Hsu <hsuregan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819999}

chromeos/services/multidevice_setup/feature_state_manager_impl.cc

@@ -26,7 +26,7 @@ namespace multidevice_setup {
 
 namespace {
 
-constexpr std::array<mojom::Feature, 3> kPhoneHubSubFeatures{
+constexpr std::array<mojom::Feature, 2> kPhoneHubSubFeatures{
     mojom::Feature::kPhoneHubNotifications,
     mojom::Feature::kPhoneHubTaskContinuation};