Move magnification_enlarge_pointer aconfig to bugfix flag

This is now rolled out as a bugfix.

Bug: 355734856
Test: atest com.android.server.accessibility.magnification (with/without flag enabled)
Flag: com.android.server.accessibility.magnification_enlarge_pointer_bugfix

Change-Id: Ia08e3192577e991acda9a1293fe40a39b2f32f70
3 files changed