gha/windows: Diagnose and recover from stopped Docker service

The wait loop added in 16c0107 probes `docker version` but does not
attempt to start the service if it is stopped, leading to 30 failed
retries and a timeout when the runner's pre-installed Docker service
has not started automatically.

Add service status diagnostics and attempt to start the Docker service
on each retry if it exists but is not running. Also redirect stderr to
null so `docker version` error messages don't flood the log.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>