Modify feature flag of Personal Safety

1.Remove feature flag and let Emergency Dialer Shortcut feature always
enabled.
2.Add feature flag for Safety Hub (the bug ID to clean up this feature flag is b/118848485).

Test: Manually
Bug: 117128459
Bug: 118809382
Change-Id: I0a3819629bc579d93c682451abdf271d0b36bf59