Initialize max number of connected A2DP devices in the native stack via JNI

Pass the maximum number of connected A2DP devices from Java to the
native stack as a parameter to the init() call.

Bug: 72351654
Test: Manual: Connect to multiple A2DP devices, check the log messages
Change-Id: I0647c36fe7c6a2df2c42a60b53b5cf505160b1e6