cleanup(magnify_ime): Fix flagging for new toggles.

The View object is not set if the flag isn't enabled,
so we shouldn't call functions that expect it unless
the flag is enabled.

Fix: 418067266
Test: Run WindowMagnificationSettingsTest in ABTD
Flag: com.android.server.accessibility.enable_magnification_magnify_nav_bar_and_ime
Change-Id: I319514291d93c6fa65a12ac7b6977aaa1e17b47e