[ravenwood] Promote "ignore" to an annotation

I thought "ignore" was sort of too dangerous to use, so I was hesitant,
but it's really not much worse than "replace" anyway, so let's promote
it.

Flag: EXEMPT host test change only
Bug: 292141694
Test: Convert DisplayManagerGlobal.ignore() to annotation, and run tests.
    ($ANDROID_BUILD_TOP/frameworks/base/ravenwood/scripts/run-ravenwood-tests.sh -st)
Change-Id: I5d37412550e1755770d199e37b494727037a9d5b