avdt: add timer for monitoring delay report as initiator

Wait for remote sink device to send Delay Report when in Configured
state before sending Open command. If the remote does not send Delay
Report for 2 seconds proceed with opening channel.

Bug: 303735871
Flag: com.android.bluetooth.flags.avdt_wait_for_initial_delay_report_as_initiator
Test: atest avatar:'A2dpTest' -v

Change-Id: Ie364f7dbc9786c12d28ee293fe9b8baf0d96646f