Magnification continuous zooming/panning uses repeat keys settings

Magnification allows continuous zoom/pan control only when repeat
keys is enabled, and matches the initial timeout before behavior
repeats to repeat keys timeout.

Test: atest MagnificationControllerTest, AccessibilityManagerServiceTest, manual
Bug: b/388847283
Flag: com.android.server.accessibility.enable_magnification_keyboard_control

Change-Id: I90347125dca7beece53dad3a65469869e9084360