fix: [Factorio] Update startparameters to load the latest server autosave

[Doug-Murphy]

Swap --start-server ${serverfiles}/save1.zip launch argument with --start-server-load-latest

Description

Please include a summary of the change and which issues are fixed.

Discussion started in #4959

Type of change

• Bug fix (a change which fixes an issue).
• New feature (a change which adds functionality).
• New Server (new server added).
• Refactor (restructures existing code).
• Comment update (typo, spelling, explanation, examples, etc).

Testing

Please list the exact validation you performed and the outcome.

• Commands/tests run: docker compose up. Verified launch arguments in Docker container log.
• Result: The Factorio server launched and loaded the latest autosave.zip
• Environment used (distro/version): Ubuntu Server 24.04.5

Risk and rollback

• Risk level: Should be LOW. No one's save1.zip should be of a later version than the game's default saving mechanic of using rolling autosaves.
• Rollback plan: A simple reversion of this PR.

Breaking changes

• No breaking changes.
• Breaking changes included (describe below).

Existing users may be reliant upon the default save1.zip loading, but this would no longer be the case.

Documentation impact

• No documentation update required.
• User documentation update required.
• Developer documentation update required.

I assume user documentation may be required, but I am not very familiar with all of the docs that exist around this. I did not personally find any, but suspect I may have just missed some.

Checklist

PR will not be merged until all steps are complete.

• This pull request links to an issue.
• This pull request uses the develop branch as its base.
• This pull request subject follows the Conventional Commits standard.
• This code follows the style guidelines of this project.
• I have performed a self-review of my code.
• I have provided a detailed enough description of this PR.

Documentation

If documentation does need updating either update it by creating a PR (preferred) or request a documentation update.

• User docs: https://github.com/GameServerManagers/LinuxGSM-Docs
• Dev docs: https://github.com/GameServerManagers/LinuxGSM-Dev-Docs

I do not believe docs will require updating. The only relevant docs I found surrounding this are here but that isn't truly applicable.

Thank you for your Pull Request!