Remote Agent throws warnings that graph_nolegend has not been sanitized

[cigamit]

Describe the bug
When you view a graph from a remote data collector, if you have input validation enabled, you can get warning messages about this variable.

To Reproduce
Steps to reproduce the behavior:

1. Goto Settings and Enable Input Validation and Save
2. Log into a Remote Data Collector and View a Graph
3. Review the Cacti Log on the Main Data Collector
4. See error

Expected behavior
Log should be clear of warnings.