Mark exec and service-management commands as DEPRECATED

What does this MR do?

Adds deprecation notices for:

• exec command
• service-related commands (start|stop|restart|status|install|uninstall)

Does this MR meet the acceptance criteria?

• Documentation created/updated
• Tests
  • [-] Added for this feature/bug
  • All builds are passing
• Branch has no merge conflicts with master (if you do - rebase it please)

What are the relevant issue numbers?

Closes #2710 (closed)