fix: wait for worker to be ready before initializing (#13270)
fix: wait for worker to be ready before initializing (#13270)

fix: wait for worker to be ready before initializing

The test dispatcher waits until a worker is ready before sending the
`init` message. This guarantees that the worker process is listening for the
message. Otherwise, the worker process might miss the `init` message and
the subsequent `run` message would crash the worker.

microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright