Remove replaced BubbleMetadata methods from SDK.

Prior to finalization, we need to remove all methods which were
replaced but kept around for short-term compatibility purposes.
BubbleMetadata had a few methods that fell into this category that had
yet to be removed.

Bug: 152761169
Test: build
Change-Id: Ic9f8d600721e15119fc28d308ff1bc444d61e399

• api/current.txt[diff]
• api/removed.txt[diff]
• core/java/android/app/Notification.java[diff]