Normalize repo.pp for RHEL and CentOS

[doomnuggets]

[codylane]

@doomnuggets - I've also submitted a pull request that might also address your concern, however, my use case is that you don't use the classinfluxdb::repo::yum directly.

Instead just tell puppet whether or not you want to use the package repos by setting manage_repos=true which would probably be set in hiera or by using a the class param.

Let me know if you have questions?