Rename send_standby_on_sleep in constants and methods

Updated the name to better represent the usage of this setting.
The values of the constants remain the same to ensure compatibility.

Bug: 169145038
Test: atest HdmiCecLocalDevicePlaybackTest
Change-Id: Ieba3d94d5db52d39f717b525a8b8ed6e6587b132
8 files changed