When creating a Graph, make testing the Data Sources optional by Template

[TheWitness]

Feature Request

Is your feature request related to a problem? Please describe

Cacti in 1.2.18 introduced a new feature to test Data Sources. This test was though buggy was a step forward. Now that the bugs are fixed, there appears to be a gap in that some Data Sources, when tested can take quite a bit of time.

Therefore, it would be nice if this setting was optional by Graph Template.

Describe the solution you'd like

Make it possible so that Testing Data Sources is optional on a Template by Template basis, and make this "Default" a preset at Import time.

Describe alternatives you've considered

Thought that this should possibly be a system level setting, but after discussing it with other members of the team, decided to make it a Template level setting.

[TheWitness]

This though a fairly minor enhancement touched several files.