Fix attaching debugger before activity launch

Since a launching app has to notify the system to
finishAttachApplication, we need to ensure that we wait for debuggers
only after notifying the system of a successful start. Otherwise,
the system will kill the app after the proc_start timeout

Test: atest CtsJdwpTunnelHostTestCases:android.jdwptunnel.cts.JdwpTunnelTest#testAttachDebuggerToDebuggableApp
Bug: 261017997
Change-Id: I69afef42c691ce387d3a0e1661c028072db63b14