[system] stop starting unnecessary log input on Windows

[leehinman]

Proposed commit message

Stop starting unnecessary log input on Windows.

This is done by changing the conditional around the log input &
journald inputs.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.
• I have verified that any added dashboard complies with Kibana's Dashboard good practices

Author's Checklist

• [ ]

How to test this PR locally

1. Install on Windows
2. Should only be 2 agentbeats running for the system integration

Related issues

• Closes [system]: On Windows extra agentbeat is started #16236

Screenshots

[elastic-vault-github-plugin-prod]

🚀 Benchmarks report

To see the full report comment with /test benchmark fullreport

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 5bf075c

[lalit-satapathy]

Added @shmsr for code owner approval.