out_file: start-up check fails with <worker 0-N> directive

[fujimotos]

Describe the bug

When out_file is configured with append=true and workers > 1,
it tries to confirm that the inter-worker lock is available.

This check can cause an unexpected exception during startup if it's
combined with ranged worker directive (such as <worker 0-2>)

To Reproduce

1. Save the following configuration as fluentd.conf
2. Run fluentd -c fluentd.conf

Expected behavior

Fluentd should start up without errors.

Your Environment

- Fluentd version: v1.15.2
- TD Agent version: N/A
- Operating system: N/A
- Kernel version: N/A

Your Configuration

<system>
  workers 2
</system>

<worker 0-1>
  <source>
    @type dummy
    tag test.log
  </source>
  
  <match test.**>
    @type file
    path output.log
    append true
    <buffer>
      @type memory
    </buffer>
  </match>
</worker>

Your Error Log

out_file.rb:193:in `configure': must set FLUENTD_LOCK_DIR on multi-worker append mode (Fluent::InvalidLockDirectory)

Additional context

No response