Prevent remote polling functionality from running on main poller

[thurban]

Feature Request

Is your feature request related to a problem? Please describe

From a security perspective, functionality that is not being used should be disabled/not running. This ensures that Cacti systems that are not utilizing specific functions (i.e. Remote Poller) have a smaller risk to security issues.

Describe the solution you'd like

Functions that are specific to defined functionality should not even try to run. i.e. remote_agents.php should return if remote pollers are not used/configured.

Describe alternatives you've considered

n/a

Additional context

Add any other context or screenshots about the feature request here.

[TheWitness]

Give it a review @thurban

[thurban]

Looks good to me. Simple but effective, so single-tier Cacti servers are save from exploits from the remote_agent.php file.