* Follow the behavior to return empty if given string is empty
- AccessibilityServiceInfo#loadDescription
- AccessibilityServiceInfo#loadHtmlDescription
- AccessibilityShortcutInfo#loadDescription
- AccessibilityShortcutInfo#loadHtmlDescription
Bug: 154092127
Test: manual test
Change-Id: I77f455945c569c81cb00127a7913bae4db1b3d1c