Backport(v1.16) command: fix NoMethodError of --daemon under Windows

[kenhys]

Which issue(s) this PR fixes:

Backport #4716

What this PR does / why we need it:
To daemonize the process, the following code will be invoked on Windows:

fluentd/lib/fluent/daemon.rb

Line 13 in 89f0a76

ServerEngine::Daemon.run_server(server_module, worker_module) { Fluent::Supervisor.serverengine_config(params) }

$log variable does not exist because it has not executed Superviser#setup_global_logger method until here.
It will perform a new startup process and prepare a logger in

fluentd/lib/fluent/daemon.rb

Line 13 in 89f0a76

ServerEngine::Daemon.run_server(server_module, worker_module) { Fluent::Supervisor.serverengine_config(params) }

This patch will only avoid the error since a logger is not required this process.

Docs Changes:
Not needed.

Release Note:
The same as the title.

[kenhys]

git switch -c backport-pr4716 --track origin/v1.16
git cherry-pick 713b738d9ac4a9321bbeb550b415311a6478747b