What does this PR do?

It reverts the following PRs:

• Revert "Add a standalone test scenario for fleet server mode (Add a standalone test scenario for fleet server mode #978) (Add a standalone test scenario for fleet server mode (bp #978) #988)"
• Revert "Uniquify the stand-alone step for checking agent status (Uniquify the stand-alone step for checking agent status #993) (Uniquify the stand-alone step for checking agent status (bp #993) #997)"

Why is it important?

Fleet Server is available from 7.13 and beyond, so it does not apply to 7.11.x

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have run the Unit tests for the CLI, and they are passing locally
• I have run the End-2-End tests for the suite I'm working on, and they are passing locally
• I have noticed new Go dependencies (run make notice in the proper directory)

Author's Checklist

• Fleet Server does not apply to 7.11