Use grantManageKeyGesturesToRecents flag for granting recents key gesture events

Reason: Recents app can only listen to key gesture events after ag/33295605, which is gated by a read only flag, com.android.window.flags.grant_manage_key_gestures_to_recents.

Test: atest WmTests:PhoneWindowManagerTests
Flag: com.android.window.flags.grant_manage_key_gestures_to_recents
Bug: 406452076
Change-Id: Ife54c640e73ca68b016d0d7279184a61167df5bc