AccessibilityService description not internationalized.

1. AccessibilityServiceInfo loading the description string on
   creation and using this value. Hence, changing the locale
   results in reporting incorrectly localized string. Added a
   new loadDescription method to return the localized version.

2. Deprecated the old method.

bug:5807616

Change-Id: Id82bda3c6a90fa6681b035d20da0b8688ed68da3