SRADA-216: Wait for start tracing finished before process stop in DA CLI.

SRADA-216: Wait for start tracing finished before process stop in DA CLI.

DA is not able to stop tracing correctly while DAState is in PREPARE_START.
Due to that the blocking until the preparation finished is needed in
TracingProcess.startTrace() before return.

* ProcessManager.TRACING_PROCESS_STOP_TIMEOUT - changed to 8sec, time measured
on Tizen_2.4 mobile emulator, enough to start tracing before process stop.
* ProcessManagerTest.BASE_TIMEOUT_MS - updated correspondingly to
TRACING_PROCESS_STOP_TIMEOUT value.
* TracingProcess.startTrace() - added blocking until tracing preparation
finished.

Change-Id: I7c176e0458999b85439edfa5e855c959f6fff66c