The touch exploration capability is dynamically granted pre-JellyBeanMR2.

Since the enable touch exploration capability is dynamically granted by
the user for apps targeting pre-JellybeanMR2 API level, we have to avoid
caching copies of the service info.

Framework change:https://googleplex-android-review.googlesource.com/#/c/301722

bug:8633951

Change-Id: I2b409ca92931d1409e885d6f54e0f10cbece2e80