Update ConnectivityDiagnosticsCallback function name.

API Council feedback suggests renaming ConnectivityDiagnosticsCallback
'onConnectivityReport' function to be 'onConnectivityReportAvailable'.

Bug: 150598997
Test: atest FrameworksNetTests
Change-Id: Ieea727ecee6cf358a53a215fd4b06233dfe967ea
(cherry picked from commit 324b224cc48fcb12125bd1727be70ad2effbfce3)
6 files changed