Cache remove_app_switch_drops flag

All of these new flags are not cached by default, so let's cache them to
avoid impacting performance.

Bug: 308729073
Test: TEST=inputflinger_tests; m $TEST &&
$ANDROID_HOST_OUT/nativetest64/$TEST/$TESTCache
remove_app_switch_drops flag

Change-Id: I3cfe29bf0538a0b88b14d59841328d43b6269972
1 file changed